Caramelized Onion Tart with Gorgonzola and Brie Recipe

Ingredients

• 2 tablespoons extra virgin olive oil
• 4 cups sliced onions, sliced root-to-top into 1/4-inch thick slices (about 2-3 med onions)
• 1 tablespoon brown sugar
• 2 tablespoons balsamic vinegar
• 1/2 teaspoon salt
• 1/2 teaspoon pepper
• 8 oz frozen puff pastry (defrosted a couple hours in the fridge)
• 2 oz chilled Brie cheese, rind removed and diced
• 2 oz Gorgonzola or other blue cheese, diced
• 2 tablespoons chopped fresh tarragon