Choux pastry

Why

When flour is tipped into boiling water and butter and stirred briefly over the heat, the starch gelatinises into a thick, smooth paste, and some water evaporates at the same time, so the paste can take up a lot of egg and still hold its shape. The eggs go in only once the paste has cooled to about 50 °C, otherwise they start to set in it; they make the dough supple and glossy, and in the oven their proteins form elastic walls. In a hot oven the water in the dough turns to steam, which inflates it from inside into a hollow bubble, and only when the proteins and starch in the walls have set does the puff hold its shape on its own. Opening the oven or taking the puffs out while the walls are still soft lowers the temperature, the steam inside condenses and the dough collapses; steam left inside a baked puff makes it soggy as it cools. Traditional Spanish churros are made only from flour scalded with boiling salted water, without eggs, and they are fried rather than baked (see the Deep-frying in oil card).

How to do it

• Bring water, or water and milk, to the boil with the butter and salt until the butter melts; take off the heat, add the flour all at once and stir in quickly.
• Return to low heat and stir for 1–2 minutes, until the dough comes away from the sides and leaves a thin film on the bottom of the pan.
• Transfer the dough to a bowl and let it cool for a few minutes, until you can keep your hand on the side of the bowl for 10 seconds; only then add the eggs.
• Add the eggs in portions and the last one only a little at a time: the dough should be glossy and fall from the spoon in a broad triangle, not run.
• Bake in an oven preheated to 200–220 °C and do not open it for the first 15 minutes; then lower the heat if you like and bake until the walls are deep golden and firm.
• Slit the baked puffs on the side, let them dry in the switched-off oven with the door ajar and fill them only once cool; keep puffs filled with custard or cream in the fridge.

If it goes wrong

Dough that is too runny after the eggs can only be thickened with another small batch of paste made without eggs and mixed in. Slit puffs that have collapsed and are damp inside and return them for 5–10 minutes to an oven heated to 180 °C so they dry and firm up; they will not puff again. Refresh unfilled puffs that have softened by the next day for 5 minutes at 180 °C and let them cool.