According to tradition, it was the Italian pastry chef of Catherine de’ Medici who invented pâte à choux, this classic of French pastry-dom (although technically it’s a paste rather than a pastry). But it seems like chou pastry was around in Roman times, and was mentioned in Apicius, and like so much of ancient knowledge, revived in the Renaissance.
Pâte à choux is made with butter and water boiled together, to which flour and then eggs are added. It is then piped out of a pastry bag in the desired shape—long for éclairs, round for profiteroles, etc.
Like Yorkshire puddings, choux relies on heat to make the pastry rise in the oven, although it can also be fried as beignets (the name was originally pâte à chaud).
Image by EXEAIR