Melt Some Clarified Butter
Roux (pronounced "roo") is one of the basic thickening agents in the culinary arts. Used primarily for thickening sauces and soups, roux is made from equal parts fat and flour, and the "equal parts" are measured by weight, not volume.
[Also see: Thickening a Sauce with Roux]
Traditionally, a roux is made with clarified butter, and that's what we'll be doing in this tutorial. But you can certainly make a roux using unclarified butter.
In fact, you can use any fat you like. For instance, this creamy potato chowder recipe uses a roux made from rendered bacon fat. And the classic pan gravy uses fat from the roasted chicken or turkey.
Start by melting a couple tablespoons of clarified butter in a pan.