Creme caramel is cooked in a bain-marie in order to achieve a slow and gentle transmission of heat to the egg mixture. If the egg custard is not cooked in a bain-marie, the oven heat will go directly into the mixture and cook it too quickly, resulting in a custard that contains air bubbles and a grainy or curdled texture. If this does happen there is no remedy. Immersing the dish in cold water will help to stop the cooking process quickly, but it may already be too late for rescue.
Small air bubbles, giving the custard a pitted appearance, can also be created if cold milk was used to make the custard instead of milk that was heated first. You should have no problems with air bubbles if you follow the recipe closely.
** Asian Recipes