For perfect baked custards, creme brulees and cheesecakes, a recipe will often recommend setting them in a bain-marie, or water bath, when they go in the oven. It's a nifty trick to better regulate the cooking temperature in recipes that rely mostly on eggs for their structure.
Because eggs are extremely sensitive to heat, they require a gentle, even temperature - no more than 212 degrees F. (100 degrees C.) - so they don't cook too quickly and curdle or split. The water bath works by absorbing the heat and distributing it gently and evenly around the custard.
Follow these steps to assemble a bain-marie and achieve creamy custard results every time.
Place the filled ramekins, custard dishes, or whole cheesecake dish into a roasting pan or other baking vessel. For ample water circulation, the outside pan should be wide enough to leave a 1 to 2 inch edge around the inside dish(es) and the sides should be high enough to hold about an inch of water.
Pull the centre rack halfway out of your preheated oven and carefully place the roasting pan on it.
Using a kettle or other spouted pitcher, pour very hot tap water carefully into the roasting pan until the water reaches the level called for in the recipe - usually 1 inch high or halfway up the sides of the custard. If you want to make it easier, you can remove one of the custard cups and pour the water into that empty spot, replacing the cup when you're done.
Gently slide the oven rack back into place, taking extra care not to slosh the water around.
Check the water level a few times during baking and replenish if necessary.
When the custard is cooked, pull the rack halfway out again and carefully remove the dish(es), letting the roasting pan remain in the oven with the door ajar until the water is cool enough to pour off.
Bake using a bain-marie and achieve perfect results every time with any of these egg-based bake-shop worthy treats: