Goat Cheese and Caramelized Onion Tarts

1 . Stage

Cut thawed puff pastry into six 3- to 4-inch rounds using a cookie cutter. Roll edges of each pastry slightly to form 6 small tarts. Set aside.

2 . Stage

Heat olive oil in a skillet over medium-high heat; stir in sweet onion. Cook and stir until onion has softened and turned translucent, about 5 minutes. Reduce heat to low and continue cooking and stirring until onion is very tender and dark brown, about 40 minutes more. Remove from heat and set aside.

3 . Stage

Preheat the oven to 350 degrees F (175 degrees C).

4 . Stage

Bring 1/3 cup balsamic vinegar to a boil in a saucepan. Reduce heat and let simmer until thickened, 5 to 10 minutes. Stir in 2 tablespoons balsamic vinegar and brown sugar. Remove from heat and set aside.

5 . Stage

Divide cooked onions between the 6 tart shells and place on a baking sheet. Sprinkle goat cheese evenly on top of each tart.

6 . Stage

Bake in the preheated oven for 7 minutes. Remove from the oven and drizzle each with balsamic vinegar reduction.

7 . Stage

Return tarts to the oven and continue to bake until cheese is bubbly and tarts are golden brown, about 8 minutes more.