Cream Sauce

1/4 cup (1/2 stick) butter
1/2 cup all -purpose flour
1 cup milk
1 cup half-and-half
Salt to taste

1. In  medium-size saucepan, melt the butter over low heat, gradually add the flour, and whisk till the mixture is foamy, about 3 minutes.

2. Remove the pan from the heat and gradually add the milk and half-and-half, whisking constantly till smooth. Season with salt, return to pan to moderate heat, and cook, whisking constantly, till thickened, about 5 minutes. (For a thinner sauce, add a little more milk.)

Mushroom Cream Sauce: Melt 2 tablespoons butter in a small skillet over moderate heat, add 1 cup finely chopped mushrooms, and cook, stirring til the mushroom liquid has evaporated, about 3 minutes. Add the mushrooms to the cream sauce before it has thickened, adding a little more milk before the final whisking.