1 (2 lb.) bag frozen hash browns
1 can cream of mushroom soup
1/2 c. butter, melted
1/2 c. onion, chopped
1 (6 oz.) carton sour cream
2 c. cheddar cheese, shredded

Spread hash browns in greased 9 x 13 pan. Blend soup, butter, onion and sour cream. Pour mixture over hash browns and sprinkle cheese on top. Bake 1 hour at 325 degrees.