1 c. macaroni, cooked
3 med. potatoes, cooked and mashed
1/4 lb. American cheese, grated
1 med. onion, chopped
1 stick butter

Melt butter; add onion and saute until golden. In an ungreased baking pan, put alternating layers of macaroni, potatoes, and cheese. Pour melted butter and onions on top. Bake at 375 degrees for 30 minutes.