Cheesy Hash Browns

1 (2 lb.) pkg. frozen hash browns
1/2 c. onion, chopped
1/2 c. melted butter
1 c. sour cream
1 can cream of mushroom salt
1 (8 oz.) jar Cheez Whiz
2 c. corn flakes (opt.)

In casserole, combine all ingredients. Bake at 350° for 30 to 45 minutes. Stir gently, once or twice. If using corn flakes, sprinkle on top last 10 minutes. Serves 8.