What is a Bain Marie? - Mary's Bath

Bain-Marie is French for "Mary's bath". According to one rumour the bain-marie is refering to the gentle water temperature that the Virgin Mary prefered. 

In cooking a bain marie is a water bath used when baking recipes that require insulation to promote even cooking.  It is used in delicate recipes such as custards, bread puddings and sometimes cheesecakes.  It is also sometimes used on the stove top to keep sauces warm.

The baking dish or dishes are placed into a baking pan that will hold the water for the bath. Then the outer baking pan is filled part way (usually about 1/3) up the sides of the baking dish with hot water. It can be difficult if not dangerous to fill the bain marie on the counter and then balance the whole lot placing into the oven.

The best practice is to place the baking pan without water onto the oven rack (with the baking dishes inside) and then fill the pan with the hot water at the oven.  This way you are not carrying a heavy pan with hot water from counter to oven.

When creating a water bath for baking custards don't use boiling water as it may overcook them by raising the temperature too quickly.

For even more insulation some recipe call for a towel to be folded and lining the bottom of the pan the food is placed in although this is rarely neccessary. The towel can also help keep ramkins from sliding on the pan. Instead of the towel you could use a silicone baking mat. The silcone mat has the benefit of not needed to be wrung out after use.

Hot custard baking cups and ramekins can easily slip from your hands when lifting out of a bain marie.  To get a better grip try using kitchen tongs that are coated with silicone.  You can also wrang wide rubber bands around the ends of metal tongs to create the same effect (and at less cost) than silicone coated tongs.  The best way to remove the hot baking dishes is to use rubber coated canning tongs that are available in canning and preserving kits.