Caramelized Onion Brie Tarts

Caramelized onion brie tarts are a good appetizer featuring rich, creamy brie cheese and sweet, golden-brown caramelized onions served on crisp, bite-sized crispy puff pastry.

These tarts are our absolute favorite indulgent appetizer for parties and addition to picnics. Brie cheese works as the base for the sweet and succulent caramelized onions and the brie is the boat that holds it all together. Once you have tried these you will be hooked!

At Avdaye, we add lots of tips in all of our recipes – because we are a home cook without any formal training, and we find we are more confident making dishes when we understand why it works, and what each ingredient means to the flavor of a recipe. Our goal is for even the most beginner home cook to feel empowered in the kitchen.

How to Make Sweet Onion Brie Bites

First assemble the following ingredients:

• Puff pastry (3 sheets) – Puff pastry offers a light, flaky texture with a rich, buttery flavor, serving as a delicate and crisp foundation.
• Yellow onions (2) – Yellow onions provide a robust, slightly sweet flavor that deepens and sweetens further when cooked, adding a hearty depth to the tarts.
• Salted butter (2 tbsp) – Salted butter imparts a creamy, rich taste with a subtle hint of saltiness, enhancing the flavors of ingredients.
• Balsamic vinegar (1 ½ tbsp) – Balsamic vinegar adds a complex, slightly sweet, and tangy flavor with a hint of woodsy richness, ideal for balancing and enhancing savory tarts.
• Sea salt (? tsp) – Sea salt offers a clean, straightforward saltiness that enhances the natural flavors of ingredients without the bitterness of iodized salt.
• Brown sugar (½ tsp) – Brown sugar contributes a deep, molasses-like sweetness, adding a rich, caramelized flavor to the onions.
• Wheel of Brie Cheese (8oz) – Brie cheese is known for its creamy, rich texture and mild, buttery flavor with earthy undertones, making it a versatile and luxurious addition to these tarts.

Once you have assembled the ingredients, use this Method:

Prep

Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper or a silicone nonstick baking sheet. Set aside.

Cook Onions

Melt the butter in a small saucepan over medium heat. Add the onions and cook, stirring occasionally, for at least 20 minutes until deeply brown and they smell sweet. Add the balsamic vinegar, salt, and brown sugar. Cook for another 5 minutes to reach a consistency similar to jam. Set aside to cool.

Cut Pastry

Cut the puff pastry into squares. Use a knife, cut an L shape on the bottom and right hand side. Cut another upside down L shape on the other side of each piece.

Boat Pastry

Gently place the cut corner over the pastry so it rests on the opposite side. Do the same with the other side. This should have a boat-like effect where each tart now has an outer edge to hold the filling in. Brush egg wash around the outside.

Add Cheese

Place a piece of brie into each tart square.

Top and Bake

Add some caramelized onion on top of the cheese. Place the tarts on the prepared baking sheet then bake for about 20 minutes or until golden brown. Remove the tarts from the oven, some cheese may leak out during cooking which is fine. Enjoy!

Kitchen notes

Selecting Ingredients: Use good quality puff pastry for the best results. For the onions, choose varieties like Vidalia or Walla Walla, known for their sweetness. The brie should be ripe but firm, making it easier to slice and melt beautifully without becoming too runny.

Seasoning: Enhance the flavors with a sprinkle of fresh thyme or rosemary over the tarts before baking. A light dusting of black pepper can add a subtle heat.

Baking to Perfection: Preheat your oven and bake the tarts until the pastry is golden and puffed, and the brie is melted. Overbaking can cause the cheese to become too runny and the pastry too hard.

Serving: Serve these tarts warm for the best taste and texture. However, they are also good at room temperature, making them a great make-ahead appetizer.

Adding a Glaze: For an extra touch of flavor and shine, brush the caramelized onions with a bit of balsamic glaze before baking.

Variations: Feel free to add other ingredients like chopped nuts for crunch, a sprinkle of blue cheese for a sharper flavor, or even some crispy bacon bits for a savory twist.

Storing and Reheating: If you have leftovers, store them in an airtight container in the refrigerator. Reheat in the oven or toaster oven to maintain the pastry's crispness.

A few answers

Can we make these tarts ahead of time?

Yes, you can prepare the caramelized onions in advance and store them in the refrigerator for up to 3-4 days. Assemble and bake the tarts shortly before serving for best results.

What type of onion is best for caramelizing?

Sweet onions like Vidalia or Walla Walla are ideal for caramelizing due to their high sugar content. However, regular yellow onions also work well.

How do we prevent the puff pastry from becoming soggy?

Prick the pastry with a fork before adding toppings, which allows steam to escape and keeps the pastry crisp. Also, avoid overloading the pastry with too much topping.

How long does it take to caramelize onions?

It typically takes about 30-45 minutes to properly caramelize onions over low heat. The key is to cook them slowly to bring out their natural sweetness without burning them.

Can we add other ingredients to the tarts?

Absolutely! Feel free to experiment with additions like chopped nuts, bacon bits, or different herbs for varied flavors.

What's the best way to serve these tarts?

These tarts are best served warm. However, they can also be enjoyed at room temperature, making them a versatile choice for gatherings.

Can we use a different type of cheese?

While brie is a classic choice for its creamy texture, you can use Camembert, goat cheese, or even a sharp cheddar as alternatives.

How should we store leftover tarts?

Store any leftovers in an airtight container in the refrigerator and consume within 2-3 days. Reheat in the oven or toaster oven to maintain the pastry's crispness.

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Ingredients

• 3 rectangular sheets puff pastry, thawed in refrigerator
• 2 yellow onions, sliced thin
• 2 tbsp salted butter
• 1 ½ tbsp balsamic vinegar
• ⅛ tsp sea salt
• ½ tsp brown sugar
• 1 egg
• 1 tsp water
• 8 oz wheel of brie

Method

1. Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper or a silicone nonstick baking sheet. Set aside.
2. Melt the butter in a small saucepan over medium heat. Add the onions and cook, stirring occasionally, for at least 20 minutes until deeply brown and they smell sweet.
3. Add the balsamic vinegar, salt, and brown sugar. Cook for another 5 minutes to reach a consistency similar to jam. Set aside to cool.
4. Cut the puff pastry into squares. Use a knife, cut an L shape on the bottom and right hand side. Cut another upside down L shape on the other side of each piece. See process picture.
5. Gently place the cut corner over the pastry so it rests on the opposite side. Do the same with the other side. This should have a boat-like effect where each tart now has an outer edge to hold the filling in.
6. In a small bowl whisk the egg with about 1 tsp of water till frothy.
7. Brush each pastry square with the egg wash.
8. Place a piece of brie into each tart square then add some caramelized onion on top of the cheese.
9. Place the tarts on the prepared baking sheet then bake for about 20 minutes or until golden brown.
10. Remove the tarts from the oven, some cheese may leak out during cooking which is fine. Enjoy!