Pastry

Shortcrust and puff pastry can be made from flour, fat, water and salt alone, and could hardly be less alike. The difference is entirely in how the fat is distributed.

In shortcrust the fat is dispersed as small particles coating flour, interrupting gluten strands so the baked result crumbles. In laminated pastry the fat is kept as continuous sheets between dough layers, so it melts and releases steam that pushes the layers apart.

Understanding that one distinction explains most pastry faults, including the one where a laminated dough leaks butter and bakes flat: the fat stopped being sheets and became dispersed.

The family sorts cleanly into three, and the sorting is by method rather than by name.

RUBBED IN. Solid fat worked into flour until it coats the particles as small pieces. Shortcrust, sweet pastry, a scone at the edge of the family. The fat is the tenderiser, and the failure mode is working it until the pieces disappear and the gluten develops instead.

LAMINATED. Fat kept whole and folded between sheets of dough, so it stays as continuous layers. Puff, rough puff, croissant, Danish. The fat is the leavener, by way of the steam it releases, and the failure modes are all about temperature: too warm and the layers merge, too cold and the fat fractures.

BRUSHED BETWEEN SHEETS. Filo is the third way, and it inverts the problem — the dough is stretched impossibly thin and the fat is painted on afterwards rather than worked in. It makes layers without ever making a laminated dough.

And choux is in this family by convention rather than by mechanism. It is a cooked paste raised by its own steam, with no fat distribution question in it at all; it is filed here because that is where a reader looks for it.

Recipes for this family are unusually insistent about cold hands, cold water, cold marble and resting in the fridge, and the reason is the same one in every case: solid fat only stays solid within a range.

Warm the fat past that range and it stops being a discrete thing distributed through flour. In a shortcrust it soaks into the flour and the pastry turns greasy and tough rather than short; in a laminated dough it merges with the dough and the layers are gone before the oven sees them. Neither is recoverable, because nothing puts a dispersed fat back into pieces.

The less obvious half is that too cold is also a failure, and a different one. Fat below its plastic range is brittle rather than pliable, so rolling shatters it into shards and the dough closes around the gaps. The result has no layers for the opposite reason, and it looks quite different: fractured rather than merged.

This is why BakeHQ publishes no temperatures for it. The usable range depends on the fat, and the reliable instruction is to watch how the dough behaves rather than to trust a number written for somebody else's butter.