Caramelized Onion & Blue Cheese Puff Pastry Tarts

Golden puff pastry topped with sweet, slow-cooked caramelized onions, tangy blue cheese, and a drizzle of honey. These Caramelized Onion & Blue Cheese Puff Pastry Tarts are a perfect combination of savory and sweet, ideal for a special brunch or as a fancy appetizer for your next gathering.

Whenever I serve these tarts, they’re a guaranteed hit with my family. My husband has always been a fan of bold flavors, and these tarts combine the deep sweetness of caramelized onions with the tang of blue cheese in a way that has become a household favorite. These tarts make frequent appearances during holiday gatherings and special occasions. What I love most is how something so elegant can come together with simple ingredients and minimal effort!

Why These Caramelized Onion & Blue Cheese Puff Pastry Tarts?

Sweet & Savory Balance: The rich, caramelized onions paired with the sharpness of blue cheese and the touch of fig jam create a perfect balance of flavors.
Beautiful Presentation: The golden puff pastry with a flaky crust looks and tastes gourmet, but it’s easy enough for a weeknight treat or a last-minute gathering.
Versatile: Serve these tarts warm or at room temperature, making them ideal for any occasion from brunches to cocktail parties.
Effortless but Impressive: With store-bought puff pastry and a few simple ingredients, you can whip up these elegant tarts without spending hours in the kitchen.

Ingredients

1 package puff pastry (490 grams / 17.3 oz), thawed in the fridge overnight
2.5 pounds onions (1.1 kg), white or yellow, halved and thinly sliced (about 1/8 inch thick)
1 tablespoon butter (14 grams / 0.5 oz)
1 tablespoon olive oil (15 grams / 0.53 oz)
1 teaspoon granulated sugar (4 grams / 0.14 oz)
1 tablespoon dry white wine (15 ml / 0.5 oz)
Kosher salt, to taste
1 egg, beaten
9 oz. fig jam (255 grams)
5 oz. crumbled blue cheese (140 grams)
2 teaspoons fresh thyme leaves (2 grams / 0.07 oz)
Honey, for drizzling

Directions

Caramelize the Onions: In a large pot, heat butter and olive oil over medium heat. Add the sliced onions and stir to coat. Cook for a total of 60 minutes, stirring every 4-5 minutes. After 10 minutes of cooking, add a pinch of salt. At the 30-minute mark, reduce the heat to medium-low and continue stirring. At 40 minutes, sprinkle in the sugar to enhance caramelization. Keep stirring until the onions are dark brown. Once done (after 60 minutes), pour in the white wine to deglaze the pan, scraping up any browned bits. Set the onions aside.
Prep the Puff Pastry: While the onions are finishing up, preheat your oven to 400°F (200°C). Unroll both sheets of puff pastry. Cut each sheet along the seams to create 6 rectangles, then cut each rectangle into 3 squares, giving you a total of 18 squares. Using a knife, gently score a half-inch border around each square to create a crust.
Assemble the Tarts: Place the pastry squares on two parchment-lined baking sheets, spaced about 1 inch apart. Brush the outer edges of each square with the beaten egg to encourage a golden crust. In the center of each square, spread 1 teaspoon of fig jam, followed by 1 teaspoon of caramelized onions, and 1 teaspoon of crumbled blue cheese.
Bake: Bake the tarts for 18-20 minutes or until the puff pastry is golden and crispy. The crust should be deeply browned and flaky.
Finish & Serve: Once baked, remove the tarts from the oven. Sprinkle fresh thyme leaves over the top and drizzle with honey. These tarts are delicious served warm or at room temperature.

Notes

Make Ahead: You can caramelize the onions a day or two in advance and store them in the fridge. When you’re ready to bake, assembly will take just a few minutes!
Cheese Alternatives: Not a fan of blue cheese? Swap it out for goat cheese or feta for a milder flavor.
Storage Tips: These tarts keep well at room temperature for a few hours, making them perfect for parties. Any leftovers can be stored in an airtight container in the fridge and reheated in the oven.
Vegan Option: For a vegan version, substitute the butter with plant-based margarine, use vegan puff pastry, and opt for a dairy-free cheese alternative.