Source: Simply Recipes

Yield: 12 servings

Ingredients

• Olive oil: 2 Tablespoons
• Medium onions, sliced root-to-top into 1/4-inch thick slices: 2 Each
• Brown sugar: 1 Tablespoons
• Balsamic vinegar: 2 Tablespoons
• Salt: 1/2 Teaspoons
• Pepper: 1/2 Teaspoons
• Frozen puff pastry defrosted a couple hours in the fridge: 1 Each
• Chilled Brie cheese, rind removed and diced: 2 Ounces
• Gorgonzola, diced: 2 Ounces
• Chopped fresh tarragon: 2 Tablespoons

=Instructions=

Heat oil in a large deep pan on medium-high heat. Add onions and cook for about 10 minutes or until wilted and starting to brown. Add sugar, vinegar, salt and pepper. Reduce heat and cook gently, uncovered for 20-25 minutes or until richly caramelized. Add a little water if the onions look like they are starting to dry out. Cool.
Roll pastry into a 10-to-14-inch rectangle (or whatever shape you want). Place pastry on a baking sheet lined with parchment paper. Prick with a fork at a couple inch increments to prevent the pastry from forming big bubbles while baking.
Spread onions over pastry, all the way to the edges of the pastry. Dot with cheese. Sprinkle with tarragon. Refrigerate if not baking immediately.
Bake in a preheated oven at 400ºF for 18-20 minutes or until cheese has melted and pastry is crispy. Cool for 5 minutes. Cut into wedges or squares.