1. Bring the milk, onion, bay leaf, parsley, and peppercorns to a simmer in a medium saucepan over low heat. Remove from the heat and let stand for 20 minutes. Strain.

2. Melt the butter in a clean medium saucepan over low heat. Whisk in the flour and let bubble without browning for 1–2 minutes.

3. Gradually whisk in the warm milk. Boil over medium heat, whisking almost constantly. Reduce heat and simmer, about 5 minutes, until the sauce is smooth and thick. Add the nutmeg and season with salt and pepper.

Variations:

Cheese Sauce: Stir ¾ cup shredded sharp Cheddar and 1/8 tsp dry mustard into the simmered sauce.