White sauce is used in a variety of dishes and is the base for many sauces. Here are the steps for a basic medium white sauce, with adjustments for other thicknesses
How to make White Sauce:
Slightly warm the milk in a saucepan over a low heat and, in a separate pan, melt the butter. Add the flour to the butter and cook over a medium heat, stirring continuously, for about 3 minutes. Don't allow the flour to brown. Slowly add the warmed milk, beating the mixture with a hand whisk (or fork) as you do so. Continue to whisk the mixture until the sauce thickens, then cook gently for about 2-3 minutes over a low heat stirring occasionally until it reaches a rich and creamy consistency. If it is too thick, you can add a little more milk. Season with salt and pepper to taste.
To begin with, you may wish to buy ready-made sauces or the packets of dry powdered sauce to which milk is added. However, there are a few very basic sauces (this is one of them) that are very simple to make and which taste so much better for being home-made.