1/4 c. chopped onion
1/4 c. butter
1/4 c. all-purpose flour
2 1/2 c. milk
5 lg. potatoes

To make sauce: Cook onion in butter until tender, but not brown. Stir in flour, 1/2 teaspoon salt. Add milk. Cook and stir until thickened and bubbly. Add 3/4 cup shredded Cheddar cheese. Stir until melted.

Place half of the sliced potatoes in a greased 2-quart casserole dish. Cover with half sauce. Repeat layers. Bake covered, stirring once. Uncover, bake 30 minutes more or until done. Makes 4-6 servings.