Caramelized onion and Gruyère tart is a rustic appetizer made from caramelized sweet onions, Gruyère cheese, and homemade pie crust.  It’s the perfect elegant quiche for brunch or dinner.

Prep Time: 30 minutes
slice of caramelized onion & Gruyère tart on a plate
Breakfast, Christmas, Family Pies

Caramelized Onion and Gruyère Tart

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This post was originally published on December 1, 2017.

Our family enjoyed this delicious caramelized onion and Gruyère tart for the first time twelve years ago, and it’s still a favorite!  The rich flavors of the caramelized onions and Gruyère cheese are superb together, especially when complimented with lots of herbs.  Keep scrolling for the step-by-step photos and tips.

caramelized onion & Gruyère tart with a slice cut out

How to Store Leftover Onion Tart

  • Place on a plate and cover tightly with plastic wrap.
  • Refrigerate for up to 3-5 days.

holding a plate of caramelized onion & Gruyère tart with a fork

Can you freeze onion tart?

  • You can freeze before or after baking.
  • Before Baking: Use milk instead of cream.  Flash freeze the tart on a cookie sheet until hard, then wrap in two layers of aluminum foil and freeze for up to 1 month.
  • After Baking: Cut in individual slices for ease.  Place in a zip-top freezer bag, press out excess air, seal, and freeze for up to 1 month.

slice of caramelized onion & Gruyère tart with a fork

How to Reheat Caramelized Onion Tart

  • Oven: Bake at 375 F for 15-45 minutes (depending on whether the quiche is frozen or not), or until desired temperature.
  • Microwave: Microwave on high for 45-60 seconds per slice, or until desired temperature.

holding a forkful of caramelized onion & Gruyère tart

How to Serve Caramelized Onion Tart

  • Salad
  • Soup
  • Roasted vegetables
  • Mashed potatoes
  • Dinner rolls
  • Roasted chicken

slice of caramelized onion & Gruyère tart with two forks

How to Make Caramelized Onion & Gruyère Tart

Gather the ingredients for the tart.  Make sure you have some pastry in the fridge, too.

ingredients for caramelized onion & Gruyère tart

Melt the butter in a skillet over medium-high heat, then add the sliced onions, bay leaf, and thyme leaves.  Lower the heat just a little and cook for 25-30 minutes, until beautifully golden brown.

When a brown coating, called the fond, appears on the bottom of the pan, pour some of the white wine into the pan and scrape the bottom to remove the fond.  This adds additional flavor to the onions and helps them not to stick.

caramelized onions in a skillet

While the onions are cooking, line a tart pan with the pastry, prick it with a fork, and chill it for 10 minutes.

Line the tart with parchment paper and fill with dried beans, then bake at 400 F for 10 minutes.  Remove the parchment and beans and bake for another 5-8 minutes, until the edges are golden brown.  This is called blind baking the pastry shell, and helps prevent a soggy crust.

a blind baked pastry shell in a tart pan

While the pastry is blind baking, grate the Gruyère cheese and mix it with a tablespoon of all-purpose flour and some dried spices.  Also, whisk together two large eggs with some heavy whipping cream.

egg and cream mixture and grated cheese mixture

Pack the Gruyère and spice mixture into the baked pie crust.

adding the grated cheese and herbs to the pastry shell

Top with the caramelized onions.

adding the caramelized onions to the pastry shell

Pour the egg and cream mixture on top.  Be careful not to spill the tart on the way to the oven–it will be quite full.

pouring the egg and cream mixture into the tart

Bake the tart at 425 F for 10 minutes, then lower the heat to 350 F and bake for 15 minutes more.  Let the tart cool for 10 minutes on a wire rack, then remove from the pan and serve.

caramelized onion & Gruyère tart on a cooling rack

Cut the tart in slices and serve while it’s still warm.  It makes a lovely brunch dish or light dinner!

slice of caramelized onion & Gruyère tart with thyme

Pro Tips for Making Caramelized Onion & Gruyère Tart

  • Give the onions plenty of time to caramelize.  If you rush the process by turning up the heat, they’ll stick to the pan and burn.
  • Deglaze the pan a few times.  Simply pour a liquid (like white wine) into the hot pan and stir, scraping the bottom of the pan to remove the brown fond.
  • Use homemade pastry.  It’s simple to make and tastes so much better!  I recommend using my favorite pastry recipe.
  • Don’t roll the pastry too thin or too thick.  About 1/8 inch thick is ideal.  Overly thick pastry is dry and unappetizing, while overly thin pastry will crack and break.
  • Blind bake the pastry to prevent a soggy crust.  It’s a simple step you can do while the onions are caramelizing.  See the step-by-step photos for this process.

I encourage you to make this caramelized onion and Gruyère tart during special holidays like Easter, Mother’s Day, or Christmas.  Honestly, this tart tastes wonderful anytime of the year including the summer.  There’s some work involved, but it’s totally worth every minute!

tart pan, cake lifter, wooden turner, and pot

Our Go-To Kitchen Tools for Caramelized Onion & Gruyère Tart

Looking for more quiche inspiration?  Check out these tasty ideas.

slice of quiche Lorraine on a plate with forks slice of onion, thyme, and goat cheese tart with a fork and the rest of the tart

The pleasure of a 5-star review for this caramelized onion and Gruyère tart would be greatly appreciated.

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slice of caramelized onion & Gruyère tart on a plate

Caramelized Onion and Gruyère Tart


  • Author: Emma
  • Prep Time: 30 minutes
  • Cook Time: 55 minutes
  • Total Time: 1 hour 25 minutes
  • Yield: 8 servings 1x

Description

Caramelized onion and Gruyère tart is a rustic appetizer made from caramelized sweet onions, Gruyère cheese, and homemade pie crust.  It’s the perfect elegant quiche for brunch or dinner.


Scale

Ingredients

For the Pastry

For the Caramelized Onions

  • 1 lb. 13 oz. sweet onions (about 3 large onions)
  • 2 tablespoons salted butter
  • 1 large bay leaf
  • 2 teaspoons fresh thyme leaves
  • 1/3 cup white wine
  • 1/8 teaspoon sea salt

For the Herbed Cheese

  • 2 cups Gruyère cheese, grated (140g)
  • 1 tablespoon all-purpose flour
  • 1 teaspoon dried rosemary
  • 1/2 teaspoon dried parsley
  • 1/2 teaspoon marjoram
  • 1/2 teaspoon herbes de Provence
  • 1/2 teaspoon salt
  • 1/2 teaspoon freshly grated nutmeg
  • 1/4 teaspoon white pepper

For the Egg Filling

  • 2 large eggs
  • 1/2 cup heavy whipping cream

Instructions

Caramelizing the Onions (10 min + 25 min cooking)

  1. Peel, quarter, and thinly slice the onions.  Remove thyme leaves from their stems, then rinse them in a sieve and pat dry.
  2. Melt 2 tablespoons of butter in a large skillet over medium-high heat.  Add the onions, bay leaf, and thyme and stir to coat with the melted butter.
  3. Cook the onions for about 25-30 minutes, stirring frequently.  The onions should be very soft and rich golden brown.
  4. When a golden brown fond appears on the bottom of the pan, pour in some of the white wine and scrape the bottom to deglaze the pan.  Repeat as needed to remove the fond.  Continue cooking until the onions are a deep golden brown.

Preparing the Cheese & Egg Filling (15 min)

  1. Preheat the oven to 425 F and put a metal cookie sheet with sides in to preheat.
  2. Grate the Gruyère and toss it with the flour and spices until well combined.  Set aside.
  3. Whisk together the eggs and cream until well blended.  Set aside.

Assembling & Baking the Tart (5 min + 30 min baking)

  1. Pack the herbed cheese into the bottom of the 9-inch, bind baked pastry shell.  Evenly top with the caramelized onions, then carefully pour the egg mixture evenly over top.
  2. Set the tart on the preheated cookie sheet and bake at 425 F for 10 minutes.  Lower the temperature to 350 F and bake for 15 minutes, until a knife inserted in the center comes out clean.
  3. Let the tart cool in the pan for 10 minutes, then remove it from the pan and let it cool for another 10 minutes on a wire rack.  Serve warm.

Notes

  • Do you have extra cheese and onions that didn’t fit in the tart?  Save them to make a mini tart with leftover pastry.  If you don’t have any extra pastry in your fridge, just bake the mini tart in a buttered ramekin without the crust.
  • The pleasure of a 5-star review for this caramelized onion and Gruyère tart would be greatly appreciated.
  • 👩🏻‍🍳 Want to see our latest recipes?  Subscribe to our email newsletter to get our latest recipes, fun food facts, food puns, and behind the scenes news about our blog.
  • Category: Dinner
  • Method: Baked
  • Cuisine: French

Keywords: caramelized onion tart, onion tart, gruyere cheese

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2 thoughts on “Caramelized Onion and Gruyère Tart

  1. The onions and cheese complement each other well. This tart is delicious and I highly recommend it to anyone.🧀😍👏

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