Ingredients
1½cupswhole milk,plus extra as needed
2tbspunsalted butter
2tbspall purpose flour
1½cupparmesan cheese,grated
salt,to taste
pepper,to taste
Preparation
In the microwave (30-second bursts) or on the stovetop, warm the milk until it’s warm to the touch and a bit steamy. (It does not need to be boiling hot; just warm.) Set aside.
Melt the butter over medium heat. Sprinkle the flour over top, then whisk together using a whisk. Continue to cook the roux, whisking constantly, for 1 minute.
Add about ¼ cup of the warm milk to the roux and whisk. Add another ¼ cup and whisk some more. The roux will seize up into clumps.
Continue adding the milk in small ¼-cup increments, whisking continuously. The clumps will eventually smooth out and look like mashed potatoes, then a thick puree, and then a sauce. Once it looks like a sauce, whisk in any remaining milk.
Once all the milk has been added, continue to cook the sauce over medium heat while whisking, for 3 to 5 minutes. It’s ready when it looks like heavy cream — slightly thickened and silky.
Add all of the cheese at once. Whisk until the cheese has melted into the sauce and is no longer visible. At this point, the sauce should look quite thick and creamy.
Transfer the sauce to storage containers and cool completely. A skin will form on the surface of the sauce and the sauce will thicken to a paste-like consistency; this is normal. Refrigerate for up to 5 days, or freeze for up to a month.
