By kerrz of reddit
Servings: Makes 1 cup.
Put 1 Tbsp of butter in a sauce pan on medium-low heat, add 1 Tbsp flour to the melted butter, mix until you get a doughy consistency, and cook for a minute or two. Add 1cup of milk. Season lightly with pepper, parmesan, basil. Let it come to a boil, then immediately simmer it. It'll thicken up.