Caramelized Onion Tart

Name: Caramelized Onion Tart
Prep time: 20 min
Cook time: 40 min
Total time: 1 h
Yield: 8 servings
Ingredients: 1 1/2 cups all-purpose flour; 1/2 cup unsalted butter, chilled and cubed; 1/4 teaspoon salt; 1/4 cup ice water; 4 large onions, thinly sliced; 2 tablespoons olive oil; 1 tablespoon balsamic vinegar; 1 teaspoon fresh thyme, chopped; Salt and pepper to taste; 1 cup shredded cheese (Gruyère or Cheddar)

Highlighted under: FreshGlow Recipes

This Caramelized Onion Tart is a savory delight, featuring sweet, slow-cooked onions enveloped in a flaky pastry crust.

Created by

Emily

Last updated on 2025-12-03T19:27:27.767Z

This Caramelized Onion Tart brings together the sweetness of onions with a buttery crust, creating a perfect appetizer or light meal.

        Why You'll Love This Recipe
        Rich, sweet flavor from caramelized onions
Flaky, buttery pastry that complements the filling
Versatile dish that can be served warm or at room temperature

      

The Perfect Combination of Flavors

Caramelized onions are the star of this tart, bringing a rich sweetness that elevates the flavor profile. Slowly cooking the onions allows their natural sugars to develop, creating a deep, complex taste that pairs beautifully with the flaky pastry crust. The addition of balsamic vinegar adds a tangy depth, balancing the sweetness and enhancing the overall experience.

The choice of cheese is equally important. Gruyère offers a nutty flavor that melds perfectly with the caramelized onions, while Cheddar adds a sharp contrast. This blend of flavors makes every bite a delightful explosion in your mouth, showcasing how simple ingredients can come together to create something truly special.

Versatile Serving Options

One of the best aspects of the Caramelized Onion Tart is its versatility. It can be served warm as a comforting main dish or at room temperature as an elegant appetizer. This makes it ideal for a variety of occasions, from casual family dinners to sophisticated gatherings. Pair it with a fresh salad or a glass of wine for a complete meal.

Leftovers can be stored in the refrigerator and enjoyed the next day, making it a great option for meal prep. Simply reheat it in the oven to restore the crispness of the crust. Whether you’re serving it at a brunch, picnic, or as a side dish, this tart is sure to impress.

Ingredients

Tart Crust

1 1/2 cups all-purpose flour
1/2 cup unsalted butter, chilled and cubed
1/4 teaspoon salt
1/4 cup ice water

Filling

4 large onions, thinly sliced
2 tablespoons olive oil
1 tablespoon balsamic vinegar
1 teaspoon fresh thyme, chopped
Salt and pepper to taste
1 cup shredded cheese (Gruyère or Cheddar)

Gather all ingredients for the tart crust and filling before you start cooking.

Instructions

Prepare the Tart Crust

In a bowl, combine flour and salt. Cut in the butter until the mixture resembles coarse crumbs. Stir in ice water, a tablespoon at a time, until the dough comes together.

Wrap in plastic and refrigerate for 30 minutes.

Caramelize the Onions

In a large skillet, heat olive oil over medium heat. Add onions and a pinch of salt. Cook, stirring occasionally, for about 25-30 minutes until golden brown. Stir in balsamic vinegar and thyme, then season with salt and pepper. Remove from heat.

Assemble and Bake

Preheat your oven to 375°F (190°C). Roll out the chilled dough and fit it into a tart pan. Spread the caramelized onions evenly over the crust and sprinkle with cheese.

Bake for 25 minutes or until the crust is golden brown.

Let the tart cool for a few minutes before slicing and serving.

Tips for Perfecting Your Tart

To ensure your tart crust is perfectly flaky, make sure your butter is very cold when cutting it into the flour. This will help create those desired layers in the pastry. Don't overwork the dough; a light touch is best to avoid a tough crust. If the dough feels too sticky, add a little more flour, but be cautious not to add too much.

When caramelizing onions, patience is key. Cooking them slowly over medium heat allows for a more uniform caramelization and prevents burning. Stir occasionally, but not too frequently, to allow the onions to develop a nice golden color. If they start to stick, a splash of water or broth can help deglaze the pan and add flavor.

Customizing Your Tart

Feel free to get creative with your filling! Adding cooked bacon or sautéed mushrooms can add a savory depth to your tart. For a vegetarian twist, consider incorporating spinach or leeks for added flavor and nutrition. Additionally, experimenting with different herbs like rosemary or basil can provide a fresh twist on this classic recipe.

If you're looking for a lighter version, consider using a whole wheat flour for the crust or reducing the amount of cheese. You can also substitute some of the onions with caramelized shallots for a milder flavor. The possibilities are endless, allowing you to tailor this dish to suit your taste preferences.

Questions About Recipes

→ Can I use store-bought pastry for the crust?

Yes, store-bought pastry works well for a quicker preparation.

→ How can I store leftovers?

Store leftovers in an airtight container in the refrigerator for up to 3 days.

→ Can I add other ingredients to the filling?

Absolutely! You can incorporate vegetables like spinach or mushrooms.

→ Is this tart suitable for freezing?

Yes, you can freeze the tart before baking. Thaw and bake when ready to serve.