Also called CREAM SAUCE or WHITE SAUCE This basic French white sauce is made by stirring milk into a mixture of butter and flour, called roux. The thickness of the sauce depends on the proportion of flour and butter to milk. The amount of flour determines the thickness of the sauce. For a thin sauce: 1 tablespoon each of butter and flour per 1 cup of milk; a medium sauce: 2 tablespoons each of butter and flour per 1 cup of milk; a thick sauce: 3 tablespoons each per 1 cup of milk. Béchamel, the base of many other sauces, was named after its inventor, Louis de Béchamel, a steward to Louis XIV's.