Butter, flour, milk, salt and nutmeg are the basic ingredients required for making white sauce, or bechamel. Bechamel, or salsa di besciamella in Italian, is a mother sauce in French cuisine and is the basis for many dishes, such as pasta casseroles, cream soups, scalloped potatoes and pot pie.
A bechamel begins with a roux. Melt 5 tablespoons of butter in a medium saucepan set over medium-low heat. Add 4 tablespoons of flour, and stir the mixture until it is smooth. Raise the heat to medium, and cook the flour-butter mixture for about six to seven minutes or until it adopts a sandy color. While the roux cooks, heat 4 cups of milk in a saucepan just up to boiling point.
Add the milk 1 cup at a time to the roux, whisking constantly until the mixture is smooth. Bring the sauce to a boil, and cook it for roughly 10 minutes while stirring it constantly. Remove the sauce from the heat, and season it with 2 teaspoons of salt and 1/2 teaspoon of freshly grated nutmeg. This recipe yields roughly 3 cups of white sauce.
A classic bechamel entails the addition of a bay leaf and 1/2 onion studded with cloves right after adding the milk. Cooks also can incorporate other layers of flavor by replacing half of the milk with stock or adding freshly grated pepper instead of nutmeg.