Melt the butter in a small saucepan over medium-low heat.
Whisk in the flour and salt to form a thick paste; cook and stir until golden in color, about 5 to 7 minutes.
Slowly, whisk in the milk; cook and stir until thickened, about 5 minutes more. If needed add more milk to reach desired consistency.
Notes
Lumpy sauce: Stir the butter and flour together with a wooden spoon or wire whisk. Stir constantly as you pour in the milk so no lumps form. If there are a few lumps once your white sauce thickens, strain the sauce through a fine-mesh sieve.Variations: Stir in 1 teaspoon of chopped fresh dill and a dash of ground nutmeg with the flour; continue the steps to make a delicious sauce perfect for fish.Use this white sauce as a base for the best cheese sauce.Makes about 1 cup.