A water bath is used to gently cook delicate foods, especially egg-based dishes, to keep them from overcooking. To prepare a water bath, place a baking dish inside a larger dish or pan. Carefully pour enough warm water into the larger dish to come about half way up the sides of the smaller baking dish.
Place the pans on the oven rack before filling them with water so you don’t have to try carrying a pan full of batter in a pan half-full of water to the oven without spilling.
This slow, gentle cooking helps food cook evenly and is what gives dishes their creamy texture. Remove dishes from the water bath as soon as they’re done. Extra time in the water can also lead to overcooking.