The basis for many dishes and for other sauces
To prepare a medium white sauce, melt 2 tablespoons butter over low heat. Stir in 2 tablespoons flour; cook, stirring constantly, until the mixture is frothy but not brown (2 to 3 minutes). Gradually add 1 cup hot milk, stirring briskly until blended. Season to taste.
Bring to a boil; reduce heat to very low. Simmer for 4 to 6 minutes, stirring occasionally. If it is lumpy, strain it. Use as the basis for creamed foods and other sauces.