For instant white sauce, blend a cup each of softened butter and flour and spread it evenly in an ice cub tray. Freeze, then cut into 16 cubes and store in a plastic bag until you want to make a sauce. Then heat 1 cup milk and 1 cube, stirring until the cube is melted and the liquid is warm.
To keep cream sauces from separating, shake the pan in a back and forth motion, and add just a tiny bit more cream at the very end. This will keep your sauce from having an oily texture. This method works better than the continual motion of a wire whisk.
To prepare white sauce at the right consistency, remember 1-2-3. For each cup of milk use 1 tablespoon of flour for a thin sauce, 2 tablespoons of flour for a medium sauce and 3 tablespoons of flour for a thick sauce. Use 2 tablespoons of butter or margarine for any thickness.
When a sauce curdles, remove pan from heat and plunge into a pan of cold water to stop the cooking process. Beat sauce vigorously, or pour it into a blender and blend until smooth.