The bain-marie, also known as water bath, is a technique used to cook foods evenly and gently. The concept is simple: Place a ceramic container of food into a large, shallow pan of warm water, then place it in the oven or on the stove as a way to control the even spread of heat. This process is used in dishes like custards, soufflés and mousse. Ever melted chocolate or made a hollandaise sauce using a double-boiler? That’s a bain-marie, too.