Did you know? Choux is the French word for “cabbage,” and choux pastry forms little irregular cabbage-like balls that are hollow inside like popovers. Unlike popovers, choux pastry becomes firm and crisp when baked. It provides the classic container for cream fillings in such pastries as cream puffs (profiteroles) and éclairs, and also makes such savory bites as cheese-flavored gougères and deep-fried beignets, whose lightness inspired the name pets de nonne, “nun’s farts.”
Choux paste was apparently invented in the medieval times, and is prepared in a very distinctive way. It’s a cross between a batter and a dough, and is cooked twice: once to prepare the paste itself, and once to transform the paste into hollow puffs. A large amount of water and some fat are brought to a boil in a pan, the flour is added, and the mixture stirred and cooked over low heat until it forms a cohesive ball of dough. Several eggs are then beaten sequentially into the dough until it becomes very soft, almost a batter. This paste is then formed into balls or other shapes and baked in a hot oven or deep-fried. As with the popover, the surface sets while the interior is still nearly liquid, so the trapped air coalesces and expands into one large bubble.
The technique for preparing choux may seem tediously elaborate, but it’s a brilliant invention. It produces an especially rich and moist paste that the cook can shape and cook into a hollow, crisp vessel for other ingredients. Cooking the flour with water and fat tenderizes the gluten proteins, preventing them from developing elasticity, and it swells and gelates the starch to turn what would normally be a batter into a dough. The subsequent addition of raw eggs contributes the richness of the yolks and the cohesive, structure-building proteins of the whites, and things the dough into a near-batter so that air pockets in the interior will be able to move and coalesce during cooking. During the baking, the fat helps crisp and flavor the outer surface. And both eggs and fat contribute to a structure that resists moisture and stays crisp while holding the cream filling.
—From “On Food and Cooking: The Science and Lore of the Kitchen” by Harold McGee
And for your listening pleasure, here is Corinne Bailey Rae singing her song, “Choux Pastry Heart”.