In 1 ½-quart saucepan, melt butter over low heat.
Stir in flour, salt and pepper with a whisk. Cook over medium heat, stirring constantly, until mixture is smooth and bubbly; remove from heat.
Gradually stir in milk with a whisk. Heat to boiling over medium heat, stirring constantly; boil and stir 1 minute. Makes about 1 cup of sauce.
