Julia Child - The Art of French Cooking

2 TB butter       3 TB Flour
2 cups of Milk + 1/4 tsp Salt  - heated

In a heavy bottomed sauce pan, melt butter to foamy.  Add the flour and whisk until the flour/butter mix is frothy, about 2 minutes.  This is the “roux”.  Remove from heat and as soon as it stops bubbling and add all of the liquid at once.  Immediately beat vigorously with a wire whisk to blend liquid and roux, gathering in all bits of roux from the inside edges of the pan.  Set saucepan immediately over high heat and stir with the wire whisk until the sauce comes to a boil.  Boil for 1 minute, stirring.