3 tbsp. butter
1/4 c. flour
2 c. milk
1/2 c. cheese (Velveeta, Cheese Whiz, American)
Salt or onion salt if desired
3 to 4 potatoes, sliced

Melt butter in medium saucepan. Add flour, stir until smooth, add milk, stir and cook until thick. Add salt (if desired) and cheese, stir until melted. Layer potato slices and sauce in casserole dish, ending with sauce. Bake at 350 degrees for 1 hour.