There are two types of baked custards: those that are served in the molds in which they were baked and those that are served unmolded. A baked custard that is unmolded must be firmer than one that remains in its container. For that reason, an unmolded, baked custard usually contains whole eggs or a combination of whole eggs and egg yolks, as the egg whites stiffen during cooking, helping the custard to retain its shape. As a general rule, a baked custard that will be unmolded requires at least six whole eggs per liter (quart) of milk.