If you make macaroni and cheese from a box that has powdered cheese, don't use all the cheese. There's usually more than enough, anyway, so save the last teaspoon or so and put it away. When you have enough, you can make cheese sauce for your own macaroni, or for vegetables or casseroles. Mix 1/4 cup of powdered cheese with 1/4 cup of butter or margarine (or half butter and half oil) and 1/4 cup hot milk. Stir until smooth.