Give the dishes a dry rehearsal
A shallow, wide ramekin and a deep cup do not present the same shape to the heat. Changing containers can change the time needed for the center to set. For a first batch, use matching dishes so you can compare them fairly and follow a method written for that shape rather than improvising several sizes at once.
Make the custard before building the bath
Follow the recipe's order for combining eggs, sugar, and dairy. When hot liquid must enter an egg mixture, add it gradually while stirring as directed. King Arthur Baking's crème brûlée method uses this gradual addition and then strains the mixture before filling the ramekins.
Divide the mixture evenly, avoiding a dramatic difference in fill depth. Wipe spills from the dish rims before proceeding. Keep the filled dishes in the larger pan on a stable surface close to the oven, and clear a safe landing place for the finished custards while your hands are still free.
Add hot water with a controlled pour
A water bath surrounds the dishes with water to moderate the heat they receive. The Culinary Institute of America's baked-custard guidance describes its role in even, gentle baking. The water belongs around the containers, not in the custard, so a kettle or pitcher with a manageable spout is helpful.
Use the water temperature and depth specified by the recipe. King Arthur's example calls for hot water halfway up the dish sides. Add it carefully without splashing the surface. Choose a filling and loading sequence you can carry out securely; a large pan of hot water deserves slow movements and dry oven mitts.
Check the center and remove the dishes
Begin checking at the recipe's first suggested time. A small wobble and freely sloshing liquid are different observations, but appearance alone does not confirm a safe endpoint. FDA consumer guidance calls for egg dishes to reach 160 F (71 C). Check the custard's center with a food thermometer and follow any higher endpoint specified by the recipe, rather than extending baking until every part looks rigid.
Remove the custard dishes from the hot bath as directed so they stop sitting in the heated water. Cool as the recipe directs, then refrigerate within 2 hours, or within 1 hour when the room is above 90 F (32 C). The bath is a baking method, not a storage system. Record the dish dimensions with your notes so the next batch starts from the same arrangement.
Keep in mind
Use a recipe developed for baked custard; a stovetop pastry cream has a different method.
Protect against splashes and steam when handling the bath and removing individual dishes.
