Pastry cream is a very dense, rich custard. It is a staple of French desserts such as eclairs, and is generally used as a filling in baked goods. The most basic pastry cream is made with vanilla, but it can also be flavored with chocolate, lemon, orange, or other extracts. It can also be lightened slightly with the addition of heavy cream, if straight pastry cream is too dense for a particular recipe.

French filled desserts have incorporated pastry cream, or crème pâtissière, for centuries. Several neighboring nations have also adopted pastry cream for rich filled desserts ranging from zuppa inglese to some versions of cheesecake. Some cooks substitute whipped cream for pastry cream, but the two are so different that using whipped cream will fundamentally change the flavor of the finished dish. There is no reason not to use pastry cream, especially since it is so easy to make.

Start by bringing two cups of milk to a boil, along with one split vanilla bean. Stir frequently to prevent the milk from burning, and remove it from the heat just as it starts to bubble. Meanwhile, whisk six egg yolks together with one half cup sugar. When the egg yolks and sugar turn to a pale straw color, sift three tablespoons of cornstarch into the mixture and whisk again.

Pour one half cup of the heated milk slowly into the egg yolk mixture, whisking to incorporate it. Next, pour the egg yolk mixture into the heated milk pan, and whisk the mixture together until it starts to thicken. Use a very low heat during this process, to gently encourage coagulation while also avoiding burning. If you want to flavor the pastry cream with an extract such as orange or rum, add it at this time.

Pull the pastry cream off the stove and force it through a sieve to remove the vanilla bean and any large lumps. Allow the pastry cream to cool in an ice bath slightly before adding three tablespoons of unsalted butter one at a time, whisking thoroughly to incorporate after each addition. For a lighter pastry cream, add one half cup of lightly whipped heavy cream, blended with a small amount of confectioner's sugar. Next, press a sheet of plastic wrap tightly into the pastry cream to prevent the formation of a skin, and promptly refrigerate it. Use the pastry cream within three days as desired.