1 can Campbell's Cheddar cheese soup
1/2 c. milk
4 c. thinly sliced potatoes
1 sm. onion, sliced thin
1 tbsp. butter

Stir soup until smooth, gradually add milk. In buttered 1 1/2 quart casserole, arrange alternately layers of potatoes, onion and soup. Pat top with butter. Bake covered, at 375 degrees for 1 hour. Uncover and bake 15 minutes more.