This basic sauce is usually made today by whisking scalded milk gradually into a white flour-butter roux ( equal part clarified butter and flour ) , though it can also be made by whisking a kneaded flour-butter beurre maniÃ into scalded milk . It is traditionally made by whisking scalded milk gradually into a white flour-butter roux ( equal parts clarified butter and flour by weight ) . Another method , considered less traditional , is to whisk kneaded flour-butter ( beurre maniÃ ) into scalded milk .