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Caramelized Onion Tart

This is an easy-to-make Caramelized Onion Tart that uses a baked, ready-to-use short pastry crust. The happy combination of caramelized onions with the Cheddar and Parmesan cheese will bring your family around the table for a delicious brunch, lunch, or dinner.

Caramelized onion tart Featured picture0

Is this a tart, or shall we call it Caramelized Onion Quiche?

Good question, and I am glad you asked it. By definition, a tart can be savory or sweet, but a quiche is always savory, so technically, we could call a quiche to be a savory tart.

I think it all depends on where the recipe comes from and how people are used to call different dishes.

I called my recipe a tart, but you can call it a quiche if this is how you prefer. I don’t think it really matters as long as you get in the kitchen and make the recipe.

Why you should make this recipe:

  1. The recipe is easy to make and very delicious.
  2. It uses an already baked short pastry crust that you can buy in the store if you choose not to make the crust from scratch.
  3. Cooking and caramelizing onions in butter(yum) is a wonderful experience. I personally love caramelized onions and use them for different recipes, like this Authentic Mexican Bistec Encebollado- Steak And Onion. I also cook tons of onions when I make Romanian Vegetable Spread- Zacusca.
  4. Savory tarts make elegant appetizers for a dinner party, and they’re perfect for everyday eating. Serve them with a salad, and you are in for a treat.
  5. This recipe is good served hot, at room temperature, or cold.

What kind of ingredients do I need to make this Caramelized Onion Tart?

First of all, you will need a ready-baked shortbread crust. You can either buy it, or you can make it from scratch. See the recipe card at the bottom of this article that gives you also an easy recipe for the crust if you choose to make it from scratch.

  • Heavy cream– is a good choice for the recipe, as milk or half and half would be too thin for the custard. You want the tart to have an unctuous texture, and fat helps a lot in this case.
  • Lots of onions– You might need somewhere between 6-8 medium onions. See the notes in the recipe.
  • Cheddar Cheese– I like Cheddar, but if you have Gruyere, you can replace the Cheddar with it, no biggie. I saw recipes out there that use all kinds of cheese, from Feta to goat cheese and Gorgonzola.
  • Parmesan Cheese– We will use this cheese to sprinkle the top of the tart with it. It adds saltiness to the final product.
  • Other ingredients– Unsalted butter, eggs, salt, and pepper

What kind of special tools do I need for this recipe?

  • A good knife(affiliate link) for slicing the onions- nothing like a good knife that cuts. I have these knives from Amazon(affiliate link) and like them a lot. They are not very expensive, but they are sharp and stay sharp for a long time.
  • Measuring cups– You need to measure the onions, the heavy cream, and the rest of the ingredients.
  • Kitchen scale(affiliate link)– If you really want to make your life easier in the kitchen and be able to measure ingredients for both American and European recipes, you definitely need a kitchen scale.
  • A heavy bottom skillet(affiliate link)– If you click on the affiliate link, you will understand what I am talking about. I love Lodge Manufacturing Carbon Steel Skillets. They are lighter than their sisters, the Cast Iron Skillets, but heavy enough to do a great job on caramelizing foods.
  • Baking sheet(affiliate link)– We need a baking sheet for placing the tart on it and bake it.
  • Serving spatulas(affiliate link)

How To Make This Caramelized Onion Tart?

Step 1. The Crust

You will need an already baked pie shell. If you buy it, make sure it is a short-crust pastry and not the one made with Graham crackers. The Graham crackers crusts are made for sweet pies and tarts, not for savory ones.

If you choose to make the crust from scratch, the recipe is on the recipe card. Don’t be nervous. It is a straightforward recipe that doesn’t require a lot of time to make.

The recipe gives you the ingredients for a double-crust pie/tart, so use only half of it. You can freeze the other half and use it later for another recipe.

Pie dough on wooden board

Step 2. Cook the onions

  • Slice them thinly. This is basically the most consuming part of the entire recipe. You will need between 6-8 medium onions sliced nice and thin.
sliced onions on a cutting board0
  • Melt the butter in a heavy-based frying pan over medium heat. Add the onions and cook, frequently stirring to avoid burning, for 30 minutes or until well-browned and caramelized. Remove the onions from the pan and set them aside.
Caramelized onions on black skillet0

Step 3. Preheat the oven to 375F/190C.

Step 4. Prepare the custard.

Beat the eggs in a large bowl. Stir in the heavy cream and season to taste with salt and pepper. Add the Cheddar cheese and mix well. Stir in the cooked onions.

Step 5. Put the tart together.

Pour the egg and onion mixture into the baked pastry case and sprinkle with the Parmesan cheese.

Step 6. Bake.

Place tart pan on a baking sheet and bake in the preheated oven for 15-20 minutes, until the filling has set and is beginning to brown.

Remove from the oven and leave to rest for at least 10 minutes. Cut the tart into slices and serve hot or at room temperature.

Caramelized onion tart slice on plate with cucumbers and olives0

Common questions:

How do I store this caramelized onion tart?

This tart needs to be tightly wrapped and refrigerated. It is good for up to a week.

Can I serve this tart right away?

I personally like to chill this tart thoroughly before serving it. The purpose is to allow the custard to set properly so that it can be sliced cleanly. It also allows the flavors to get friendly with each other and combine.

If you are less of a perfectionist or less patient, you can serve this tart straight out of the oven, but please allow it to rest for at least 15 minutes to cool and rest.

What to serve with this dish?

Green leaves salads are an excellent choice.
Here is an idea: Toss together green leaves with halved cherry tomatoes, add 3-4 tablespoons of Parmesan cheese, and 2 tablespoons of olive oil. Season to taste and serve. OR, you can make this Belgian Endives Boston Lettuce Salad.

Caramelized onion tart close up0

Interested in more recipes of tart/quiche?

Best Quiche Recipes

Vegetarian Mini Quiche Recipe

Crustless Broccoli Bacon Quiche

Yield: 6 servings

Caramelized Onion Tart Recipe

Caramelized onion tart square photo0

This is an easy-to-make Caramelized Onion Tart that uses a baked, ready-to-use short pastry crust. The happy combination of caramelized onions with the Cheddar and Parmesan cheese will bring your family around the table for a delicious brunch, lunch, or dinner.

Prep Time 25 minutes
Cook Time 55 minutes
Total Time 1 hour 20 minutes

Ingredients

  • 9 inch ready-baked short-crust pastry
  • 7 tablespoons/3 1/2oz/100g unsalted butter
  • 5 1/4 cups/1 1/4 lb/600g onions, thinly sliced
  • 2 large eggs
  • 1/2 cup 3 1/2 fl.oz/100ml heavy cream
  • 1 cup/3 1/2 oz/100 g shredded Cheddar cheese
  • 1 cup/3 1/2 oz/100g shredded Parmesan cheese
  • Salt and pepper to taste

Instructions

  1. Melt the butter in a heavy-based frying pan over medium heat. Add the onions and cook, frequently stirring to avoid burning, for 30 minutes or until well-browned and caramelized. Remove the onions from the pan and set them aside.
  2. Preheat the oven to 375F/190C.
  3. Beat the eggs in a large bowl. Stir in the heavy cream and season to taste with salt and pepper. Add the Cheddar cheese and mix well. Stir in the cooked onions.
  4. Pour the egg and onion mixture into the baked pastry case and sprinkle with the Parmesan cheese.
  5. Place tart pan on a baking sheet and bake in the preheated oven for 15-20 minutes, until the filling has set and is beginning to brown.
  6. Remove from the oven and leave to rest for at least 10 minutes.
  7. Cut the tart into slices and serve hot or at room temperature.

Notes

Note: How many cups of onions do I need?

2 cups of sliced onions are about 8oz. You need 21oz of onion, which could mean approximately 5 1/4 cups. You will need 6 medium onions, more or less.

In case you want to make your own crust for this tart, I recommend the following Pate Brisee recipe:

  • 2 cups all-purpose flour
  • 3/4 teaspoon salt
  • 2/3 cup unsalted cold butter
  • 4-5 tablespoons cold water

How to make the pie crust(pâte brisée or short-crust pastry):
In a food processor:

  • Mix flour with salt and place in the food processor.
  • Add cold butter cut into small cubes, and pulse a few times until you obtain a mixture that resembles sand or bread crumbs. Do not overmix.
  • Add water, one tablespoon at a time, until the mixture holds together.

By hand:

  • Mix flour and salt together then cut the cold butter into small cubes and add it to the flour.
  • Use a pastry tool to incorporate the butter into the flour, or use your fingertips. You should have a mixture that resembles sand or bread crumbs.
  • Add water, one tablespoon at a time, until the mixture holds together.
  • Divide dough into two parts, then shape each half into a disk. Wrap each half in plastic foil and refrigerate until firm, about 1 hour or up to 1 day. (You can skip this part if you are in a hurry).

Note: For this recipe, use only one disk. Place the other one in the freezer and use it later for a different recipe.

How to pre-bake the crust:

  • Roll out the dough on a lightly floured surface into a 12-inch circle. Fit into a 9-by-1 1/2-inch round tart pan (or 9-inch pie dish), pressing dough into corners, extending the edges extra high to allow for shrinkage. Transfer to freezer to chill for 30 minutes. 

  • Fill at least two-thirds with baking weights—dried beans, rice, ceramic, or metal pie weights. 

  • Bake first for 15 minutes, remove from oven and let cool a few minutes. Carefully remove aluminum foil and weights.
  • Poke the bottom of the pie pan with a fork and return to the oven.
  • Bake for an additional 10 minutes or until lightly golden. (Fork holes are for any air to escape.) Transfer to a wire rack to cool while making the filling.

Nutrition Information:

Yield:

6

Serving Size:

1

Amount Per Serving: Calories: 313Total Fat: 24gSaturated Fat: 14gTrans Fat: 0gUnsaturated Fat: 8gCholesterol: 125mgSodium: 473mgCarbohydrates: 12gFiber: 1gSugar: 6gProtein: 14g

Did you make this recipe?

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