In a saucepan, melt butter over low heat. Whisk in the flour and cook the mixture, stirring for 3 minutes. Add the milk in a stream, whisking. Bring the mixture to a boil and simmer for 3 minutes. Stir in the cheese and cook until cheese is melted.
Cook the macaroni according to package instructions and drain well. Combine with cheese mixture and salt and pepper to taste.
Nutritional Value Per Serving: 294 calories, 31% from fat, 10 grams of fat, 314 milligrams of sodium
Recipes courtesy Sara Moulton