White sauce is the generic name for a whole collection of sauces having one thing in common: they are based on a roux of equal weights of butter and flour. They are called white sauces because the roux is not coloured and the resulting sauce remains white. It is the liquid that usually varies in white sauces. Technically, the sauce we know as white sauce is actually bechamel sauce, the liquid used being milk. With all white sauces the proportions are 50g butter, 50g flour and 600ml liquid to give 600ml of sauce. In all white sauces it is important to fry the roux gently to ‘cook’ the flour. This breaks up the gluten content of the flour and ensures that the resulting sauce does not have a floury taste that no amount of cooking will remove later.