Melt the butter, and when it bubbles put in the flour, shaking the saucepan as you do so, and rub till smooth. Put in the hot milk, a little at a time, and stir and cook without boiling till all is smooth and free from lumps. Add the salt, and, if you choose, a little pepper.
Cream sauce is made exactly as is white sauce, but cream is used in place of milk. What is called thick white sauce is made by taking two tablespoonfuls of butter and two of flour, and only one cup of milk.