2 tbsp. chopped onion
1/4 c. butter
1/4 c. flour
1 tsp. salt
1/2 tsp. dry mustard
Dash of pepper
1 1/2 c. milk
2 c. shredded mild Cheddar cheese
1/2 lb. ham, cut into 1/8 inch slices
6 c. cooked potatoes, sliced

Saute onion in butter. Blend in flour and seasonings. Gradually add milk; cook stirring constantly until thickened. Add 1 1/2 cups cheese; stir until melted. Toss potatoes in cheese sauce. Pour into 2 quart casserole dish, reserving 1 cup potato slices. Arrange ham and remaining potato slices on top of casserole. Bake at 350 degrees for 30 minutes. Top with remaining cheese.