Caramelized Onion Tart - cooking recipe

Ingredients

3 lb. large sweet onions, sliced
2 Tbsp. olive oil
1 tsp. salt
1/2 (17 1/4 oz.) pkg. frozen puff pastry sheet
1/2 c. shredded Parmesan cheese

Preparation

Cook onions in hot oil in a large skillet over low heat, stirring often, 30 to 35 minutes or until onion is caramel. Stir in salt and set mixture aside. Unfold pastry; fit into a 9-inch square tart pan. Bake at 400\u00b0 for 15 to 20 minutes or until browned. Remove from oven. Press pastry with the back of a spoon to flatten. Top with caramelized onions. Sprinkle with Parmesan cheese. Bake 5 more minutes.