People call it choux for short. The word literally means cabbage in French, and if you’re wondering how a pastry dough (batter, really) made of eggs, butter and flour ever got that name, reflect for a moment on the knobbly top of a cream puff and you’ll get it.
Choux dough (batter, really) is, along with the popover, among the greatest exemplars of mechanical leavening known to the bakery and pastry world. Should you be rusty on what exactly “mechanical leavening” means, it’s shorthand for raising bread and/or pastry via steam power. Laminated doughs like puff pastry use it, soufflés and angel food cakes use it. Yet none of them achieve the impressive volumes of choux, a walnut-sized dollop of which will inflate to roughly the size of a lemon in the oven — and almost perfectly hollow to boot.
What’s the magic behind it? Steam occupies something on the order of 1600 times the space of the water it came from. When you consider that most doughs and batters are quite wet, that’s a lot of leavening potential there. Even in a device as fiendishly clever as choux, most of that leavening potential escapes (otherwise you’d have a éclair as big as a living room couch, which, you know, really wouldn’t be such a bad thing), but if you’re clever about it, you can retain just enough to push up whatever it is you happen to be baking. In point of fact everything baked employes mechanical leavening to some extent. Yeast and chemicals at best create “starter” bubbles which are later expanded by steam in then oven.
Why am I telling you all of this? Honestly, because I can’t stop (it’s why I have a blog, so my friends and family don’t kill me). However I find it fascinating that choux can do what it does: start as a wet batter about the consistency of library paste and expand into a crackly golden glory some 12 times its original size, hollow and just begging to be filled up with some sort of pastry cream or ice cream.
How difficult is it to make? Not very, though it does involve multiple steps of mixing, cooking, beating and baking. The good news, however, is that you can make a big batch at one go, then freeze the finished shells in bags for months. I typically make a big batch of both round (cream puff) and elongated (éclair) shells, so I’m prepared no matter what mad craving takes hold of me.