A bain-marie is a pan of water that is
used to help mixtures such as custards bake evenly and to protect them
from the direct heat of the oven or, in some cases, the stove. Bain-marie
are usually used for dishes that are baked in small containers (ramekins
or casseroles) because the constant temperature of the water helps them
all cook at the same rate regardless of the evenness of the oven. The
water for bain-marie is usually brought to a boil on top of the stove and
poured around the containers in a pan just large enough to hold them.
Cold water would cause the food to cook too slowly.
Usually the bain-marie is placed on
the stove for a few seconds to bring the water, cooled by the ramekins,
back to the simmer. A triple layer of parchments paper or newspaper or a
kitchen towel on the bottom of the bain-marie protects the foods from the
direct heat of the stove.