2 tbsp. butter
2 tbsp. flour
1 tsp. dry mustard
2/3 c. milk
1 1/2 c. (6 oz.) shredded sharp Cheddar cheese
4 c. cubed cooked potatoes
1 1/2 c. chopped ham
1/4 c. sliced onion

Melt butter in saucepan over low heat. Blend in flour and mustard. Gradually add milk, stirring constantly until thickened. Add 1 cup cheese, stir until melted. Stir in potatoes, meat, onions. Spoon into 1 1/2 quart casserole. Bake at 350 degrees for 30 minutes. Top with remaining cheese. Cook until melted.