Orange Hollandaise Sauce
Make the sauce over simmering water instead of over direct heat; too much heat will only cook the egg yolk rather than thicken the sauce. A bowl rather than the top pan of a double boiler makes whisking the sauce easier. Finally, softened butter blends in more readily than the more commonly used melted butter.
To prevent a skin from forming on top of the sauce, cover sauce loosely with a paper towel and set over pan of warm water until ready to serve.