The food processor and microwave oven can both be used to make foolproof hollandaise and béarnaise sauces in minutes. The eggs, however, are not as well cooked as in the classic methods and the butter is melted not softened, so the sauce is not quite as creamy and silky. However, I don’t think there is anything wrong with using these modern methods, especially as it encourages people to make sauces they might otherwise be apprehensive about.
This version of hollandaise sauce, like the classic version, becomes an almost ethereal sauce if you fold in 2 or 3 stiffly whisked egg whites just before serving. This lightens the sauce, as well as increasing the volume. Béarnaise sauce can also be made by these quick methods, using the quantities opposite.