Hollandaise is an indulgent, buttery sauce that is an essential component of eggs Benedict but equally heavenly with asparagus, salmon or new potatoes. The sauce is an emulsion of egg yolks and liquid butter flavoured with lemon juice, salt and a little cayenne pepper and is notoriously difficult to get right. The trick is to heat the eggs enough so they thicken but no so much that they curdle. Our easy recipe below will help you achieve perfect results every time.