• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Marilena's Kitchen

Mediterranean Cooking With an Accent

  • About
    • About Me
    • Contact Me
  • Recipes
  • Cooking Classes
    • Private Cooking Classes
    • Personal Chef
    • Culinaria Cooking School Classes
    • Customer & Student Reviews
  • Let’s Work Together
  • Portfolio
  • Travel

Easy Tart with Caramelized Onions, Mushrooms & Gruyère

May 23, 2019 by Marilena Leavitt 4 Comments

Easy Tart with caramelized onions

When it comes to pulling together an easy appetizer I often turn to my trusty filo dough to whip up something classically Greek, like spanakopitakia or feta-stuffed filo cigars.  While they require a little planning, nevertheless, I know they will always turn out well and that they will disappear very quickly.  Because they are so easy and popular, I am always on the lookout for something different to use as a base for delicious toppings.

Recently I spotted an almost forgotten package of puff pastry in the freezer and wanted to experiment with it to see what I could come up with for an easy appetizer. I gathered a few ingredients that I had on hand that I thought would make a tasty topping:  a few onions, a package of Cremini mushrooms, two small potatoes, and some Gruyère cheese.

The first step for this recipe is to caramelize the sliced onions, low and slow, until they become sweet and golden brown.  Next, I dry-sauté the mushrooms until they release all their moisture and then I cook them in olive oil with some fresh thyme. Those ingredients alone would have made a great topping, but I thought that adding a couple of very thinly sliced potatoes would make this an even more substantial appetizer or light lunch, so added those too along with some crushed fennel seeds.

Once the topping cooled off, I rolled out the puff pastry and topped it with the caramelized onions, mushrooms and sliced potatoes. I spread some cheese over it and put it in the preheated oven.

Easy tart with caramelized onions ready for the oven

Caramelized onion and mushroom tart

I baked the tart until the puff pastry became golden, crispy and all puffed up. The only difficult part about this recipe is to wait for it to cool down. Thankfully this does not take long at all, at which point you can cut it into small squares and pass it around to your guests.  With Memorial Day coming up this weekend, this foolproof appetizer might be the star of your backyard gathering or any future outdoor entertaining this summer!

5.0 from 1 reviews
Easy Tart with Caramelized Onions, Mushrooms and Gruyère
 
Save Print
A savory tart topped with sweet caramelized onions and mushrooms and cut into appetizer-size pieces.
Author: Marilena Leavitt
Recipe type: Appetizer
Serves: 20 pieces
Ingredients
  • 1 TBSP. olive oil
  • 1 TBSP. butter
  • 2 med. yellow and/or red onions, thinly sliced
  • ½ TBSP. brown sugar
  • 2 TBSPS. Balsamic vinegar
  • --- --- sea salt & freshly ground pepper
  • 8 oz. Cremini mushrooms, cleaned and thinly sliced
  • 1 TBSP. fresh thyme
  • 2 sm. Yukon Gold potatoes, thinly sliced
  • 1 tsp. fennel seeds, toasted and crushed (optional)
  • --- --- sea salt & freshly ground pepper
  • 1 sheet frozen puff pastry (½ of a 17oz. package)
  • (defrosted & thawed according to directions on package)
  • 4 oz. Gruyère cheese, grated
Instructions
  1. Heat a large saucepan over medium-high heat. When the pan is hot, add the olive oil and the butter together, followed by the sliced onions. Cook for about 10 minutes or until the onions wilt and start to brown. At that point add the next three ingredients (sugar, vinegar, salt and pepper). Reduce the heat and cook gently, uncovered for about 20 more minutes or until the onions are completely caramelized. Add a little water if the onions look like they are drying out. Taste and adjust the seasoning. Remove the onions to a separate bowl.
  2. Add the sliced mushrooms to the same pot and sauté (without oil) for a few minutes until they release their moisture. At that point, add a little olive oil and the thyme leaves and cook for a few minutes, stirring frequently. Once the mushrooms start lightly brown, add the sliced potatoes and the fennel seeds. Season everything with some salt and pepper and cook for a few more minutes, until the potatoes soften a little. Set the mixture aside to cool.
  3. Unfold the thawed sheet of puff pastry and place it on a work surface. Roll it out into a 10”x14” rectangle and remove it to a baking sheet lined with parchment paper. Prick with a fork every few inches to prevent the pastry from bubbling while it bakes. Using a very sharp knife, score the perimeter of the dough about ¼- to ½-inch from the edge.
  4. Spread the cooled onions evenly over the puff pastry. Top with the sautéed mushrooms and potatoes and sprinkle with the Gruyère cheese. (Refrigerate if not baking immediately).
  5. Preheat the oven to 375°F. Bake the puff pastry on the middle rack for 25-30 minutes or until the cheese is bubbling and crust is nice and golden. Allow the tart to cool for 10 minutes then cut it into 20 little rectangles. Serve warm or at room temperature.
Notes
1. If you wish, you can make an egg wash with one egg and one tablespoon of water, and brush it around the edges of the tart before baking.

2. Using one sheet of puff pastry, you can also form 6 individual tartlets, round or square.
3.5.3240

Easy Tart with onions and mushrooms

THANK YOU FOR READING AND FOLLOWING ALONG

If you are not already following my blog, please subscribe to Marilena’s Kitchen to have every new post delivered right to your inbox!

I love hearing from you, please leave me a comment below.

Share this:

  • Click to share on Pinterest (Opens in new window)
  • Click to share on Twitter (Opens in new window)
  • Click to share on Facebook (Opens in new window)
  • Click to share on Tumblr (Opens in new window)
  • Click to email a link to a friend (Opens in new window)
  • Click to print (Opens in new window)

Like this:

Like Loading...

Related

Filed Under: Appetizers Tagged With: BBQ appetizers, caramelized onions, easy appetizers, easy entertaining, easy puff pastry recipe, Memorial day appetizers, Memorial day BBQ, mushroom tarts, onion tarts, puff pastry appetizers

Previous Post: « Grilled Lemon Chicken Wrapped in Pita with Tzatziki
Next Post: Easy Filo Swirls with Feta and Thyme »

Reader Interactions

Comments

  1. Janice Gartner says

    December 25, 2020 at 6:34 PM

    Delicious!

    Reply
    • Marilena Leavitt says

      January 5, 2021 at 2:16 PM

      So glad you liked it, Janice! Such an easy and delicious recipe!

      Reply
  2. Krystyna Smith says

    October 22, 2021 at 7:16 PM

    Oh my goodness ? it was amazing…(trendy word). Thanks for your time in this recipe. We love it ❣️ I baked a small pork roast, applesauce and your recipe (onion tart) delish!!!

    Reply

Trackbacks

  1. Rustic Caramelized Onion and Wild Mushroom Tart Recipe | Perfect for Spring says:
    February 15, 2025 at 8:14 AM

    […] Explore pairing suggestions from Marilena’s Kitchen. […]

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Rate this recipe:  

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Primary Sidebar

  • Email
  • Instagram
  • Pinterest
Marilenas-Kitchen-Author-Bio
marilenas-kitchen-author-bio

more about me

Search

Marilena Leavitt

INSTAGRAM

Mini filo tartlets with almond custard and fresh b Mini filo tartlets with almond custard and fresh berries 🍓A delightful springtime dessert that is light, seasonal, and elegant at the same time 🌼 Crispy filo layers form the base, with a delicious almond pastry cream custard, fresh strawberries and toasted almonds on top - so delicious! 🍓
.
A new recipe in collaboration with my friends at @fillofactory 
.
✨You can find this recipe on the blog [marilenaskitchen.com], linked also in bio! ✨
.
.
#springdessert #strawberries #tarts #baking @fillofactory #bakingtime #sweettreats #bakingfromscratch #dessert #bakingwithfruit #fillofactory #Easterdessert #bakedwithlove #mothersdaydessert #fromscratch #thefeedfeed #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #gastronomia #eatrealfood  #photooftheday #yummyfood #easybake #onthetable #foodphotography #marilenaskitchen
Braided Mini Greek Sweet Rolls - the smaller versi Braided Mini Greek Sweet Rolls - the smaller versions of the traditional Greek Easter bread (tsoureki), a bread that everyone makes for Easter in Greece! 🧡 It is a brioche-like, slightly sweet, yeasted bread made using eggs, milk, and butter. 🧡 A delicious breakfast bread, the perfect accompaniment to a hot cup of coffee or tea! 🧡☕️ 🫖☕️
.
✨ New recipe on the blog, linked in profile and in stories 👩🏻‍🍳✨
.
#breadrolls #bread #Greekbread #Easterbread #tsoureki @kingarthurbaking #braidedbread #fromscratch #thefeedfeed #bakingathome #feedfeedbaking #foodblogfeed #makeitdelicious @thefeedfeed #foodstyling #droolclub #myfoodphotography #buzzfeast #foodfluffer #foodphotographer #photooftheday #yummyfood #realfood #sweetreats #foodphotography #foodiesfeed #heresmyfood #thebakefeedfeed #marilenaskitchen 

.
Crisp Spring Salad with a refreshing Greek yogurt Crisp Spring Salad with a refreshing Greek yogurt dressing: seasonal, bright and tender vegetables that pair so well with this delicious, creamy dressing! So, so good! 🥗🥬🥒🌿
.
🌿Recipe linked in bio & on the blog: [Marilenaskitchen.com]👩🏻‍🍳🌿
.
.
.
#springsalad #summersalads #vegetarian #healthyrecipes #salad #homemadefood #instagood #greekdish #mediterraneandiet #yogurtdressing #greekfoodblogger #yummyfood #mygreektable #thefeedfeed #mediterraneanliving #huffposttaste #yahoofood #bonappetitmag #buzzfeedfood #epicurious #feedyoursoul #dailyfoodfeed #eathealthy #eattherainbow 
.
.
Crispy spiral filo pie with spinach, artichokes, s Crispy spiral filo pie with spinach, artichokes, shallots, fresh herbs and Feta cheese 🌿🌀 A delicious spring recipe inspired by the classic Greek spanakopita. Wholesome, flavorful vegetarian dish, perfectly crispy and flaky in every bite! 🌿
.
🌿This is a new recipe, in collaboration with my friends at @fillofactory 
.
🌿 Recipe linked in profile and on my blog [Marilenaskitchen.com] 👩🏻‍🍳
.
.
#savorybaking #filo #filopastry  #appetizer @fillofactory #bakingtime #fromscratch #thefeedfeed #spinachpower #bakingathome #feedfeedbaking #foodblogfeed #fillofactory #makeitdelicious @thefeedfeed #foodstyling #droolclub #myfoodphotography #buzzfeedfood #buzzfeast #foodphotographer #photooftheday #yummyfood #realfood #eattheworld  #foodphotography #foodiesfeed #heresmyfood #thebakefeedfeed #marilenaskitchen
My favorite orange almond cake, made with almond f My favorite orange almond cake, made with almond flour and semolina flour. 🍊🍊 A super moist, not too sweet “snack cake”, with a great nutty flavor and a pronounced citrus flavor. So, so good, perfect with a cup of coffee and a great treat to have around the house for anytime of the day! 🍊🍊
.
✨Recipe linked in profile, and on my blog [Marilenaskitchen.com] ✨
.
.
#orangecake #coffeecake @kingarthurflour #bakelove #dessertsofinstagram #snackcake #mediterraneancuisine #bakefromscratch #fromscratch #greekfoodblogger #almondcake #thefeedfeed #foodblogfeed #droolclub #thecookfeed #thebakefeed #makeitdelicious @thefeedfeed #f52food #comfortfood #huffposttaste #hautescuisines #gastronomia #buzzfeast #eatrealfood  #photooftheday #yummyfood #realfood #onthetable #allrecipes #foodphotography
Creamy Hummus with Crispy Homemade Pita Chips: a d Creamy Hummus with Crispy Homemade Pita Chips: a delicious and healthy recipe, full of good plant-based protein and fiber, a staple in the Mediterranean diet! ✨💯😋
.
✨New recipe on my site [marilenaskitchen.com], linked in bio!✨👩🏻‍🍳
.
Ingredients:
1 15 oz. can chickpeas, rinsed, drained, and with their skin removed
2-3 cloves garlic
¼ cup tahini (sesame seed paste)
3 TBSP. fresh lemon juice
pinch of ground cumin
pinch of Cayenne pepper (optional)
½ tsp. sea salt
⅓ cup ice-cold water 
.
(Full recipe on my site)
.
.
#hummusrecipe #pitachips #homemadepitachips #savoryfood #easydips #partyfood #gamesnacks  #appetizerideas #bluezoneskitchen #Mediterraneandiet #fromscratch #foodandwine #thefeedfeed #foodblogfeed #comfortfood #huffposttaste #gastronomia #buzzfeast #homemade #eatrealfood  #photooftheday #yummyfood #snack #foodphotography
Tiropitakia - traditional Greek filo triangles fil Tiropitakia - traditional Greek filo triangles filled with Feta cheese and a tiny amount of spearmint 💙✨Crispy filo layers and sharp Greek Feta, such a delicious flavor and texture combination! 😋 Nobody can resist this favorite Greek snack! ✨💙🇬🇷
.
.
✨Full recipe on my site [marilenaskitchen.com], linked in bio!✨👩🏻‍🍳
.
~ INGREDIENTS:

• ½ lb. Greek feta cheese, crumbled
• ½ lb. ricotta cheese (full fat) or Greek anthotiro (if you can find it)
•1 large egg, beaten
• ¼-½ tsp. sea salt
• ¼ tsp. freshly ground pepper
• ½ lb. filo dough, thawed
• ½ cup extra virgin olive oil, for brushing on the filo 
.
.
.
#filoappetizers #gamedayfood #tiropitakia #τυροπιτάκια  #greekfood #greekrecipes #filo #tiropitakia #greekgastronomy #filosnacks #Mediterraneandiet #fromscratch #Greeksnack #greekfoodblogger #foodandwine #thefeedfeed @dodoni_international #mediterraneanlifestyle #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #greekchef #hautecuisines #gastronomia #buzzfeast #eatrealfood  #fetacheese #yummyfood #allrecipes #lovefood #foodphotography #marilenaskitchen
Cold, winter Sundays call for comfort food: oven-r Cold, winter Sundays call for comfort food: oven-roasted chicken with small red potatoes and lots of fresh lemon and garlic! A super simple and delicious recipe! ✨😋👌
.
.
✨Full recipe on my site [marilenaskitchen.com], linked in bio!✨
.
.
#roastedchicken #sundaydinners #comfortfood #chickenrecipes #familymeals #buttermilkchicken @ciaosamin #saltfatacidheatcookbook
Light as a cloud vegetable frittata with lots of F Light as a cloud vegetable frittata with lots of Fontina cheese, a delicious dish - not only for breakfast or weekend brunch, but also for those busy weeknight evenings!  So, so good! 😋🌶️🌿🧀 🍠
.
✨Full recipe up on my site [marilenaskitchen.com], linked in bio!✨
.
.
#frittata #breakfastrecipes #savorybreakfast #brunchtime #fromscratch #thefeedfeed #bakingathome #myfoodphotography #mediterraneandiet #makeitdelicious #photooftheday #realfood #eattheworld  #foodphotography #thebakefeedfeed #marilenaskitchen
Mini filo quiches with salmon and chives: a delici Mini filo quiches with salmon and chives: a delicious and easy holiday appetizer! A box of good quality filo shells, some smoked salmon, and a simple custard of eggs & cream is all you need to make these flavorful little savory bites! 🥂🎄😋
.
🎄A new recipe in collaboration with my friends at @fillofactory🎄
.
✨You can find this recipe on the blog [marilenaskitchen.com], also linked in stories!✨
.
.
.
#appetizerideas #holidayappetizer #brunchideas #filoappetizer #savorybaking @fillofactory #bakingtime #filodough #greekfoodlovers #fillofactory #bakedwithlove #greekgastronomy #bluezoneskitchen #Mediterraneandiet #fromscratch #foodandwine #thefeedfeed #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #hautecuisines #gastronomia #buzzfeast #todayfood #eatrealfood  #photooftheday #yummyfood #greektreats #filorecipes #onthetable #foodphotography
A delicious holiday appetizer: four-ingredient Puf A delicious holiday appetizer: four-ingredient Puff Pastry Parmesan Cheese Straws with fresh rosemary and sesame seeds! ✨😋 Crispy and flaky, savory and so flavorful, they are the perfect addition to a holiday buffet and any charcuterie board! ✨🧡💯
.
This new recipe is a collaboration with my friends at @fillofactory 🧡
.
✨Find the recipe on the blog [marilenaskitchen.com], linked also in bio! ✨
.
.
#cheesestraws #puffpastryrecipes #appetizerrecipe #vegetarianappetizer #savorybaking @fillofactory #bakingtime #greekfoodlovers #fillofactory #bakedwithlove #bluezoneskitchen #Mediterraneandiet #fromscratch #foodandwine #thefeedfeed #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #hautecuisines #gastronomia #buzzfeast #todayfood #eatrealfood  #photooftheday #yummyfood #greektreats #filorecipes #onthetable #foodphotography #marilenaskitchen
Delicious Greek meatballs, creamy tzatziki and red Delicious Greek meatballs, creamy tzatziki and red onion slivers, ready to be wrapped in toasted pita bread! An all-time favorite family meal! 😋🥙 💙🇬🇷
.
✨Recipe linked in profile! 👩🏻‍🍳✨
.
.
.
#Greekmeatballs #keftedakia #greekcuisine #comfortfood #instagood #greekdish #mediterraneandiet #greekfoodblogger #yummyfood #mygreektable #thefeedfeed  #mediterraneanliving #huffposttaste #yahoofood #bonappetitmag #yummyfood #weeknightmeals #buzzfeedfood #epicurious #feedyoursoul #dailyfoodfeed #saveurmag #appetitejournal #allrecipes #marilenaskitchen
Spiced Apple and Cheddar Cheese Filo Treats - a gr Spiced Apple and Cheddar Cheese Filo Treats - a great way to celebrate the beginning of fall baking! 🍂🍎🍁
Crispy, buttery, flaky filo cups make the base for a delicious apple and spice filling. The addition of cheddar cheese adds an unexpected layer of flavor to this easy fall dessert! 🧡🍂🍎
.
🍂A new recipe in collaboration with my friends at @fillofactory 🧡🍂
.
✨You can find this recipe on the blog [marilenaskitchen.com], linked also in bio! ✨
.
.
#fallbaking #apples #bakingwithapples @fillofactory #bakingtime #sweetandsavory #bakingfromscratch #falldessert #bakingwithfruit #fillofactory #cabotcheese #bakedwithlove #Mediterraneandiet #fromscratch #thefeedfeed #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #gastronomia #eatrealfood  #photooftheday #yummyfood #easybake #onthetable #foodphotography #marilenaskitchen
Tiropsomo, a delicious Greek skillet bread with Fe Tiropsomo, a delicious Greek skillet bread with Feta cheese, oregano and lots of good extra virgin olive oil - such an irresistible treat! 🧡🍞Super easy to make even for the novice baker, a favorite accompaniment to every Greek meal! 🇬🇷💙😋
.
✨A favorite recipe from my blog, linked in profile! ✨👩🏻‍🍳
.
.
.
#Greekbread #cheesebread #skilletbread #τυρόψωμο #freshbread #breadbaking #bread #bakingtime #fromscratch #goodmoodfood #thefeedfeed #foodblogfeed @thefeedfeed #droolclub #myfoodphotography #buzzfeast #eatrealfood  #makeitdelicious #photooftheday #yummyfood #realfood #eattheworld  #foodphotography #foodiesfeed #heresmyfood #chefsofinstagram #marilenaskitchen
A delicious plum puff pastry tart ✨the flavor of A delicious plum puff pastry tart ✨the flavor of cardamom-infused plums is a match-made-in-heaven! ✨ A wonderful combination of sweet and slightly tart plums that pair so well with the deep, earthy flavor of freshly ground cardamom! So, so good! 🧡😋 
.
✨ A new recipe in collaboration with my friends at @fillofactory 🧡 
.
✨You can find this recipe on the blog [marilenaskitchen.com], linked also in bio! ✨
.
.
.
#easydessert #fruitart #puffpastry @fillofactory #bakingtime #plums #bakingfromscratch #falldessert #bakingwithfruit #greekfoodlovers #fillofactory #bakedwithlove #greekgastronomy #Mediterraneandiet #fromscratch #thefeedfeed #foodblogfeed @thefeedfeed #comfortfood #huffposttaste #hautecuisines #gastronomia #eatrealfood  #photooftheday #yummyfood #greektreats #easybake #onthetable #foodphotography #marilenaskitchen
Follow on Instagram

PINTEREST

Archives

my foodgawker gallery

Terms of Use

© Marilena Leavitt and Marilena’s Kitchen, 2025. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Links may be used, provided that full and clear credit is given to Marilena Leavitt and Marilena’s Kitchen with appropriate and specific direction to the original content. 

Copyright © 2025 · Foodie Pro Theme by Shay Bocks · Built on the Genesis Framework · Powered by WordPress

 

Loading Comments...
 

    %d