Waterbath, Water Bath or Bain Marie

Vanilla Flan with Caramel Sauce TutorialA waterbath (water bath) or Bain Marie (Bain-Marie) is where a smaller container, filled with the substance to be heated, fits inside the outer container, filled with hot liquid (usually water), and the whole is heated at, or below, the base, causing the temperature of the materials in both containers to rise as needed. The insulating action of the water helps to keep contents of the inner pot from boiling or scorching. It is used with baking recipes containing large amounts of eggs, such as baked custards, including cheesecakes and flan.

The Double Boiler Method is different.

When a waterbath is filled with water the maximum temperature of the material in the lower container will not exceed 212 degrees F (the boiling point of water at sea level). Using different working liquids (oils, salt solutions, etc.) in the lower container will result in different maximum temperatures.
SARAH SAYS: Gentle cooking, such as baking custard without starch in a waterbath, keeps the egg proteins loose and soft until the mixture gets hot enough, at around 160 degrees F.

This how to baking technique is used with the Vanilla Flan with Caramel Sauce Tutorial

Prepare a Waterbath:

1. Place the caramel-lined soufflé dish in a deep baking pan. Pour the mixture into the soufflé dish.
NOTE: The mixture will almost come up to the top of a 4 cup soufflé dish.

2. Add enough water to the outer pan so that it goes halfway up the sides of the smaller dish.
NOTE: In some recipes, boiling-hot water is used.
SARAH SAYS: The resulting waterbath allows the flan custard to bake low and slow, helping the prevent overbaking or cracking and other problems.

3. Bake for xx to xx minutes, until the custard is set in the center and lightly browned on top.
The custard will still be quite wiggly in the center when its container is tapped lightly on its side with the handle of a wooden spoon.
4. Remove the smaller dish from the water and let cool.

5. When the water has cooled, remove the pan containing it from the oven, and discard the water.

Prepare a Springform Pan for a Waterbath:
SARAH SAYS: I like to bake my cheesecakes in a 9-inch cake pan. But, for those who like to use a springform pan, a 9- or 10-inch size is fine. To prevent water leaking in from the waterbath, what I like to do is sit the filled cheesecake pan in the bottom of a 15 x 17-inch Reynolds Hot (ovenproof) Foil Bag, used to bake foods in, in a larger pan used for the waterbath. Gather the bag around the sides of the pan. It shouldn't be closed over the top of the cake. The bag is shaped like a lunch bag. The water won't leak in because the bag is sealed on all sides except for an opening in the top.) Then, fill the waterbath pan with hot water.

If you do not have a foil bag, use a wide sheet of heavy duty foil:

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