Eclairs, fruit pastries, napoleons and other little treasures of the patisserie usually have one thing in common: pastry cream. Pastry cream, or creme patisserie, is an egg-enriched custard with flour or cornstarch for added thickening power, used to fill or layer pastries.
It's quite similar to vanilla pudding, and super easy to make. The recipe here only includes three egg yolks, considerably less than a traditional French recipe - which can include up to ten. We like the lighter flavor, and we usually use pastry cream in recipes that don't need a very thick texture. If you do, however, just add additional egg yolks. The resulting cream here is light, delicatedly flavored with vanilla, and very, very creamy. Be watching for a recipe later this week that puts it to good use!
Heat the milk to boiling. Meanwhile, whisk the egg yolks, sugar and flour together. Whisk in a little warm milk, then a little more, gradually. Whisk well then pour into the boiled milk. Turn the heat to low and cook, whisking constantly, until thickened - about 3 or 4 minutes. Whisk in the butter and vanilla. Transfer to to a bowl and cover with plastic wrap touching the surface of the cream. Refrigerate.