1 stick butter
1/2 lb. Velveeta cheese, cubed
1 can cream of mushroom soup
3 c. milk
1 1/2 onion, chopped
2 c. mushrooms
2 1/2 lb. potatoes, sliced

In casserole pan, grease side of pan top to bottom. Layer potatoes, add bits of above ingredients on each layer until pan is full. Bake in oven at 350 degrees for 2 hours or until done.