Custard Tips

Of all liquids, milk has the greatest tendency to boil over, so this is a particular hazard when making custard-based desserts that require scalding or boiling milk or cream. Milk and cream contain casein proteins, which gather near the surface as they heat. Once the milk or cream comes to a boil, steam bubbles rising from the bottom are forced through the protein-rich layer at the top. The proteins stabilize the bubbles, keeping them from bursting, so they rapidly increase in number. The simple solution is to heat dairy in a big, wide pan.

For many custards and sauces, we provide both a visual cue—like “the custard will coat the back of a wooden spoon”—and a temperature; these should eliminate any anxiety about when to take the custard off the heat and will help you avoid overcooking. Also, we provide a doneness temperature for some recipes, which is a clearer signal than deciding how to interpret visual cues like “until centers are barely set. Need to check the temperature of a custard or caramel sauce but there isn't much volume in the pan? Simply tilt the pan to use your instant-read thermometer properly and to avoid having the stem touch the bottom of the hot pan.

Lumps can form if a custard becomes overheated. You may think it's a lost cause, but there is a simple fix. If you notice lumps beginning to form, immediately pour the custard out of the pot and into a bowl. Pulse it with a hand-held immersion blender in 5-second intervals until it's nearly smooth. Be careful not to over process or you will end up with irreparably thin, watery custard. Pour the blended liquid through a fine-mesh strainer to remove any remaining lumps and continue with the recipe. Don't use a blender or food processor; they incorporate too much air and will leave the mixture frothy.

Egg-based puddings and custards can curdle if cooked beyond 185 degrees. We take crème anglaise off the heat when the mixture registers 175 degrees, but when making the base for ice cream we push the temperature to 180 for maximum thickness. When done, baked custards such as flan and crème brûlée should jiggle (but not slosh) when gently shaken. This will occur between 170 and 175 degrees. For some custard desserts, such as crème caramel, you will know they are done when a paring knife slipped in halfway between the center and edge comes out clean.