Place butter or margarine in a glass measuring cup. Microwave at full power for 45 seconds or until melted. Blend in flour, salt and pepper to a smooth paste. Microwave at full power 30 seconds. Whisk in milk. Microwave at full power for 3 to 3-l/2 minutes or until thickened and bubbly, whisking three times. Sauce should be thickened and smooth.

Stir cheese into hot white sauce. Microwave at full power 30 seconds or until cheese melts. Stir or whisk until smooth.

Combine cheese sauce and macaroni. Bake in 350 degree oven until it bubbles and top is brown.