It is hard to believe that only fifty years ago Sauce Beurre Blanc was scarcely known outside southern Brittany and the mouth of the Loire. It was brought to Paris by a woman chef, Mère Michel, who served the classic pike with Sauce Beurre Blanc at her restaurant. The sauce makes good use of regional ingredients: white Muscadet wine, shallots, and unsalted butter from the region of Charente.