1 (32 oz.) pkg. hash browns, thawed
1/2 stick butter
1/2 c. chopped onion
1 can cream of mushroom soup
1 c. Cheddar cheese
1 c. sour cream

Place in greased 9 x 13 inch pan. Top with 2 cups crushed cornflakes. Dot with butter. Bake at 350 degrees for 40-45 minutes.