¼cupfinely grated strong-tasting cheese,such as Gruyère or Parmesan
In a medium saucepan set over low heat, combine the milk, onion wedge, bay leaf, cloves, and some freshly grated nutmeg. Simmer very gently, uncovered, for 15 minutes. Strainthe milk to a measuring cup and discard the onion, bay leaf, and cloves.
Wash the saucepan and return to medium-low heat. Melt the butter, then whiskin the flour. Cook, whisking continuously until the mixture (called a"roux") is just fragrant, about 2 minutes. Remove from the heat andslowly whisk in the warm milk. Return the saucepan to medium-low heat and cookwithout boiling, whisking constantly, until the sauce reaches the consistencyof a thick cream soup, 8 to 10 minutes. Remove from the heat and whisk in thegrated cheese. Season with salt and pepper, to taste.
Use the sauce immediately, or transfer to an airtight container andrefrigerate for up to 3 days. The cold sauce will remain spreadable so you canuse it on the pizza straight from the fridge.