Hollandaise sauce is a blend of eggs, butter and lemon sauce. The Julia Child recipe on Food.com uses a bit of water, cayenne pepper, salt and white pepper. Martha Stewart's recipe adds water and coarse salt, but no pepper. Vinegar replaces the lemon juice in other recipes.
BettyCrocker.com's hollandaise sauce recipe uses 3 large egg yolks, 1 tablespoon of lemon juice and 1/2 cup of firm butter. Instructions say to heat the egg yolks and lemon juice over very low heat, stirring vigorously, then to add 1/4 cup of the butter and stir until the butter melts. The next step is to add the rest of the butter and stir again to melt it. The butter should melt slowly so the eggs have time to cook.
The sauce is done when it thickens. If it begins to separate, adding a tablespoon of boiling water and beating it until it's smooth will fix it. The sauce works well with vegetables such as asparagus, fish such as salmon, poultry and meats, and as the topping for eggs Benedict.