Hollanaise sauce is an emulsion of butter and lemon juice using egg yolks as the emulsifying agent, usually seasoned with salt and a little black pepper or cayenne pepper. It is a French sauce, so named because it was believed to have mimicked a Dutch sauce. Hollandaise sauce is well known as a key ingredient in Eggs Benedict. The sauce is one of the five sauces in the French haute cuisine mother sauce repertoire.