The rate at which you add a liquid to a flour-and-

butter roux can have a drastic effect on the
smoothness of the final sauce, as well as its
thickening power. To demonstrate this, try the
following experiment.

Materials

• 2 tablespoons butter


• 2 tablespoons all-purpose flour


• 2 cups milk


• 1 pound cheese, grated

Procedure

Cook 1 tablespoon of the butter and 1 tablespoon of
the flour in a small saucepan over medium heat,
stirring constantly, until light golden blond, about 1
minute. Rapidly add 1 cup of the milk, whisking to
combine. Allow to come to a boil, stir in half of the
cheese, and set aside. Repeat with the remaining
butter, flour, and milk, this time very slowly
whisking in the milk over the course of 15 seconds.