A smooth, eggy, custard is both luxurious and comforting all at once. From creamy puddings to cheesecake to ice cream to a wide range of dessert sauces, a surprising number of desserts rely on custards. These custards, in turn, rely on the thickening power of egg yolks to achieve their creamy texture.
The key to a just-right custard lies in the temperature to which the eggs are cooked and how long it takes to get to that temperature. If egg yolks get too hot or cook too fast, their proteins can clump together and separate from the liquid surrounding them, leaving you with scrambled eggs and some watery remnants. This curdling is the enemy of egg-based desserts.
A technique called tempering allows for gentler heating and also dilution of the egg proteins, which makes it harder for them to clump together. It’s done by very slowly whisking some or all of the hot liquid in a recipe (the base for pudding, lemon curd, or ice cream, for example) into the eggs off the heat before adding this mixture to the pan to finish cooking over low or medium heat. This tempering process slows the rate at which the eggs cook and ensures that they won’t curdle.
Cooking custards requires careful temperature control. An instant-read thermometer is the most reliable way to judge when your custard has reached the proper temperature, but you can also dip a wooden spoon into the custard and run your finger down its back to judge doneness. (This old-fashioned method really does work.) When the temperature is under 170 degrees, the custard will be thin and the line will not hold. When it’s in the range of 175 to 180 degrees, the custard will coat the spoon properly and the line will maintain neat edges—just
right! When exposed to temperatures higher than 180 degrees, the egg proteins will bond too tightly, and they will start to clump and separate from the liquid. Our final step is to pass the custard through a fine-mesh strainer, which guarantees lump-free, silky-smooth results.
1 Heat liquid and other ingredients as directed to simmer in saucepan.
2 Place eggs (whole eggs and/or egg yolks) in bowl; add other ingredients as directed.
3 While whisking constantly, slowly add hot liquid mixture (all or a portion, as recipe directs) to egg mixture.
4 Return combined mixture to saucepan and cook over low or medium heat, whisking, until mixture thickens and reaches correct temperature.
5 To ensure perfectly silky-smooth results, strain cooked mixture through fine-mesh strainer.