Hash Brown Casserole

1 1/2 big bags shredded hash browns
1 cup chopped onion
1 stick melted butter
1 can cream of mushroom soup
1 can cream of chicken soup
8 oz. sour cream
2 cups shredded cheddar cheese
5 cups frosted flakes, crushed
1/2 stick butter

Combine first 7 ingredients. Place in large, buttered baking dish. Comgine frosted flakes and 1/2 stick butter. Use cereal mixture to cover hash browns. Bake for 1 hour at 350.