A bain marie (bane mah-REE) is the French term for a hot water bath. It is a device that uses gentle and controlled temperatures to evenly cook and/or keep foods hot. Commonly referred to as a double boiler, a bain marie consists of a pot filled with a bit of liquid (typically water) and a second, smaller pot or bowl that rests over top. The liquid in the pot underneath is heated. The pot or bowl that rests over top actually buffers the direct heat from the liquid and prevents the contents of the top pot or bowl from rising above the boiling point. For water, this is 212° Fahrenheit (100° Celsius). This set up is particularly useful when cooking items that will ruin if overheated (i.e. Hollandaise sauce, custards and chocolate).

A bain marie is also used to cook dishes such as crème brulee. Small dishes are placed in a shallow pan and filled with warm water. The water surrounds the food with gentle, even heat to prevent it from curdling as it cooks.