Mini Onion Quiches

pre-made puff pastry or pie crust
Nonstick cooking spray
1 cup chopped onion
2 tablespoons butter
2 eggs
1 cup milk
1/2 teaspoon salt
1/4 teaspoon pepper
1 cup grated Swiss cheese (I also tried parmesan and it was good)
Preheat oven to 300 degrees F.
Cut small round pieces of pre-made puff pastry or pie crust and divide among mini muffin tins that have been sprayed with a nonstick cooking spray. Saute onion for 10 minutes in 2 tablespoons butter. Cool, then divide evenly on top of pre-made puff pastry or pie crust. Beat eggs; add milk, salt, pepper, and cheese. Pour by spoonfuls on top of onions in tins. Do not fill to top, as they will run over. Bake until set, about 15 to 20 minutes. Do not over bake. May be stored in refrigerator or freezer. Warm in oven before serving.