Caramelized Onion and Boursin Puff Pastry

Simple, but Delicious

This caramelized onion puff pastry with Boursin cheese is an approachable appetizer that’s sure to be loved by everyone. It’s made with frozen puff pastry, some crumbled boursin cheese, and a simple recipe for caramelized onions. The only difficult thing about this recipe is the patience required to get a caramelized onion!

This appetizer recipe is simply delicious. It’s herby, cheesy, salty, and sweet. A little bit of something for everyone. Make this recipe for the holidays, a weekend get-together, or even as an option to fancifier your game day spread. It’s a great dish for any occasion. 

The Supplies

Ingredients

To make this caramelized onion puff pastry recipe, you’ll need the following ingredients:

• Unsalted butter
• Olive oil
• Yellow onions
• Red onion
• Granulated sugar
• Kosher salt
• Red wine vinegar
• Frozen puff pastry
• Boursin cheese
• Lemon zest
• Egg optional
• Honey
• Flaky salt

For the exact ingredient amounts, check out the recipe card at the bottom of this page.

Equipment

In order to make this caramelized onion puff pastry, you’ll need the following pieces of equipment:

• Large baking sheet
• Parchment paper
• Cutting board and knife
• Large heavy-bottomed frying pan
• Wooden spatula
• Measuring spoons
• Rolling pin
• Microplane

Frequent Recipe Questions

Can I make this caramelized onion puff pastry in advance?

• A: This recipe is best made right before enjoying it. That said, you can assemble the tart the day of and place it in the refrigerator. Then, bake as instructed right before serving.

Does this recipe freeze well?

• A: I do not recommend freezing this recipe. The water content in the onions will change in the freezer, leaving you with a soggy tart. 

Recipe Tips

When you make this caramelized onion puff pastry recipe, here are a few tips to make sure it turns out great:

• The less often you stir the onions, the quicker they will caramelize and develop color. Use a wooden spatula to scrap any pieces that stick to the bottom of the pan to incorporate back into the onions. 
• Boursin cheese can be a little tricky to spread across the puff pastry. I find using my hands to crumble and smooth it down the easiest! Then as you’re arranging the warm onions on top, use the spoon to gently press the ingredients down. The heat from the onions will melt the cheese slightly and encourage it to spread.
• Do not use a non-stick pan or thin-bottomed frying pan for this recipe. Neither will result in the deep, even caramelization you want for the onions.

Recipe Details

Caramelize the Onions

To get this recipe started, you’ll melt a knob of butter in a large, heavy bottomed frying pan with a drizzle of olive oil. Once the butter is melted, next you’ll add a bunch of sliced onions to the frying pan, tossing them in the oil. Let the onions cook until they begin to turn soft and translucent. 

Once the onions have softened, sprinkle in a bit of salt and sugar. This step will help caramelize the onions by adding color, from the sugar, and extracting the extra water from the onions, with the salt. During this step, the onions should develop a golden brown color. Once this is achieved, pour in a drizzle of red wine vinegar to help deglaze the pan and add a deep flavor. Set the frying pan aside to let cool a bit while you get the tart together.

Assemble and Bake the Pastry

To assemble the caramelized onion and boursin tart, first roll out the thawed puff pastry into a rectangular shape. Place the pastry on a lined baking sheet and crumble the Boursin cheese across the top. Use a spoon or your hands to spread the cheese across the pastry sheet into a single layer. 

Spoon the caramelized onions over the top of the Boursin cheese and add the lemon zest. Bake the puff pastry until the pastry is golden brown and the cheese is melty. Take the baking sheet out of the oven and let it cool for a few minutes, just to set. Drizzle a bit of honey over the top of the puff pastry and then season with some flaky salt and a pinch of red pepper flakes. Slice the pastry into individual pieces and enjoy!

If you make this caramelized onion puff pastry recipe, be sure to leave a comment or give this recipe a rating – I can’t wait to hear how it goes. As always, tag me on Instagram, TikTok, or Facebook in your photos. It makes me feel like we’re getting to cook together!

This post may contain affiliate links, please see the privacy policy for details.

Print Recipe

0 Add to Favorites

Christmas

Caramelized Onion and Boursin Puff Pastry

Author: Laura Wilkins Cooking Method: Baked, Sautéed Cuisine: American Courses: Appetizer

Difficulty: Intermediate Prep Time 10 mins Cook Time 55 mins Rest Time 5 mins Total Time 1 hr 10 mins

Cooking Temp: 400  F Servings: 12

Best Season: Suitable throughout the year

Dietary:

N Nut Free V Vegetarian

Description

This caramelized onion puff pastry has a layer of herby Boursin cheese and topped with fresh lemon zest, sweet honey, and flaky salt.

Ingredients

Scale

1/2x 1x 2x 3x

Caramelized Onions

• 1 tablespoon unsalted butter
• 2 tablespoon olive oil
• 2 yellow onions, quartered and thinly sliced
• ¹⁄₂ yellow onions, quartered and thinly sliced
• 1 teaspoon granulated sugar
• ¹⁄₂ teaspoon kosher salt
• ¹⁄₄ teaspoon black pepper
• 1 teaspoon red wine vinegar

Puff Pastry

• 1 sheet of frozen puff pastry
• 2 wheels Boursin cheese
• Zest of 1 lemon
• 1 large egg (optional)
• 2 teaspoons honey
• Large pinch flaky salt, to taste
• Small pinch crushed red pepper flakes, to taste

Instructions

Do Some Prep

1. Preheat the oven to 400°F. Set out a large baking sheet and cut a piece of parchment paper to fit onto the sheet.

2. Set out the sheet of frozen puff pastry and wheels of Boursin cheese to come to room temperature.

Caramelize the Onions

1. Melt the unsalted butter in a large, heavy bottomed frying pan, such as cast iron, over medium heat. Drizzle the olive oil and let it warm for 30 seconds, swirling with the melted butter.

2. Add the sliced yellow and red onions to the pan. Toss the onions to coat them in the melted butter and oil. Let the onions cook at medium heat, undisturbed for 5 minutes. Stir the onions and continue to cook, stirring occasionally until they reduce and become translucent, about 5 additional minutes.

3. Turn the heat under the pan down to medium-low. Sprinkle the sea salt, sugar, and black pepper over the onions. Toss to incorporate and cook additional 7-8 minutes, stirring occasionally. The onions will develop a deep brown color.

4. Carefully pour the red wine vinegar into the pan and stir to incorporate. Cook for 10 more minutes, until the onions are browned and the vinegar has evaporated. 

5. Set the frying pan aside, off of the heat, to cool slightly. About 5 minutes.

Bake the Caramelized Onion Puff Pastry

1. While the onions cool, use a rolling pin to roll the puff pastry into a long rectangle and place on the prepared baking sheet.

2. Sprinkle the boursin cheese on to the center of the puff pastry and use a spoon or your hands to spread it into an even layer across the center of the pastry, leaving an inch or two along the edges for a crust. Spoon the slightly cooled onions on top and zest the lemon over the entire thing.

3. Optional step: in a small mixing bowl, whisk the egg with a splash of water. Use a pastry brush to brush the whisked egg mixture across the edges of the puff pastry. This will create a crisp, deeper brown crust.

4. Bake the caramelized onion puff pastry for 22-24 minutes, until the pastry is golden brown. Let the puff pastry cool for 5 minutes and then drizzle the honey over the top and sprinkle with flaky sea salt and crushed red pepper flakes.

5. Slice the pastry into individual portions and enjoy!