Here's the basic recipe for vanilla pastry cream:
1 1/2 cups whole milk or half-and-half
4 large egg yolks
1/3 - 1/2 cup sugar, to depending on how sweet you want it
1/4 - 1/3 cup flour, depending on how thick you want it
pinch of salt
1 teaspoon vanilla extract
In terms of equipment, you'll need:
A medium saucepan
A mixing spoon
2 mixing bowls
Here's what you do:
Heat the milk in the saucepan over medium-high heat until it's warm. Set it aside until it's cool enough to touch, but still warm. Pre-heating the milk helps to cut down on the cooking time, but you don't want the milk so hot that it will cook the eggs.
In one of the mixing bowls, whisk together the egg yolks and sugar until smooth and thick. Whisk in the flour and salt.
Slowly pour in the warm milk while whisking the egg-sugar mixture constantly. Transfer the mixture back to the saucepan.
Cook the mixture over medium heat, stirring constantly with your spoon so the bottom doesn't scorch. It will quickly start to thicken to the consistency of pudding. When large steamy bubbles start to pop through the liquid, the pastry cream is nearly done. (At this point, you're cooking the flour so your cream doesn't end up tasting chalky.)
Continue stirring for 1-2 minutes longer. Set the strainer over a clean bowl and strain the pastry cream to get out any lumps. Press a piece of plastic wrap against the surface of the pastry cream and refrigerate until you're ready to use it.
Pastry cream will keep for 5-7 days refrigerated. This recipe makes about two cups of cream, and is enough to fill one tart, one layer cake, or a batch of choux puffs.
Playing with the recipe:
This recipe makes a basic vanilla pastry cream, but it's also a good base for any other flavors you might want to add. You can infuse any number of ingredients into the milk while it's heating in the first step. Try cinnamon sticks, dried lavender, or coffee beans. You can also use any other extract besides (or in addition to) vanilla to add flavoring.
To make a chocolate pastry cream, melt a handful of chocolate (about 2 ounces) into the pastry cream in the last minute of cooking.
What kinds of things have you done with pastry cream?