I. To add flavor to this delicate sauce, you may infuse the milk first: Bring it to a boil in a medium saucepan over medium heat with 1 bay leaf and 1 thick onion slice stuck with 2 whole cloves. Immediately take off the heat, cover, and let stand for 15 minutes. Fish out the onion and bay leaf and proceed as directed.

Melt in a medium saucepan over medium-low heat:

Whisk in until well blended and smooth, about 1 ½ minutes:

Remove the pan from the heat and slowly whisk in:

Return the pan to the heat and bring to a simmer, whisking constantly to prevent lumps. Continue to cook, whisking, until the sauce is smooth and hot and has thickened, 1 to 2 minutes. If you are using this sauce as is, season to taste with:

Prepare White Sauce I, using 3 tablespoons butter, 3 tablespoons all-purpose flour, and 1 cup milk.