A velouté sauce is an adaption of Béchamel sauce (or white sauce), and is one of the classic mother sauces of French cuisine.
In preparing a velouté sauce, a light stock (one in which the bones used have not been roasted), such as chicken, veal or fish stock, is thickened with a blond roux. Substituting milk for stock would produce a Béchamel.
Thus the ingredients of a velouté are butter and flour to form the roux, a light chicken, veal, or fish stock, and salt and pepper for seasoning.
It is often served on poultry or seafood dishes, and is used as the base for other sauces. Sauces derived from a velouté sauce include Allemande sauce (by adding lemon juice, egg yolks, and cream), suprême sauce (by adding mushrooms and cream to a chicken velouté), and Bercy sauce (by adding shallots and white wine to a fish velouté).