Why Pastry Pulls In

A tart case that slumps down the sides of the tin is one of the most dispiriting sights in a home kitchen. The filling looks generous, the flavour is there, but the shell has shrunk away from the metal and the whole thing seems apologetic. The good news is that shrinkage is almost never a fault of your recipe. It is a matter of timing, technique and temperature, and all three are entirely within your control.

Pastry shrinks because gluten contracts as it relaxes, and because the fat in the dough melts before the structure has set. If you stretch the pastry when you line the tin, it will spring back the moment it hits the heat. If the butter softens too early, the walls of the case slump before they can firm up. Everything that follows is designed to prevent those two things from happening.

Line, Chill, and Trust the Fridge

Start with dough that has already rested. After mixing, flatten it into a disc, wrap it and leave it in the fridge for at least 30 minutes. This hydrates the flour evenly and gives the gluten a chance to relax before you ask it to do anything difficult.

When you roll out, work on a lightly floured surface and turn the pastry a quarter turn after every couple of strokes. Aim for a thickness of about 3mm, and lift the dough regularly so it does not stick. To line the tin, roll the pastry loosely around the pin and unroll it over the tin, letting it settle into the corners rather than pressing it down. Never stretch pastry to make it fit. Lift the edges and ease them gently into the flutes, allowing the excess to hang over the rim.

• Rest the lined tin in the fridge for at least 20 minutes, or 10 minutes in the freezer if you are short of time.
• Prick the base all over with a fork before chilling, not after, so the holes stay open.
• If the pastry feels at all soft or greasy, chill it again. Cold pastry holds its shape; warm pastry does not.

Parchment and Beans: The Weighting Rules

Cut a square of baking parchment, scrunch it into a ball, then unfold it. This makes it pliable enough to sit neatly against the sides without pushing them outward. Press it right into the corners, then fill with baking beans, ceramic weights or a generous quantity of dried pulses you keep for the purpose.

Fill to the very top of the rim. Under-filled cases are a common cause of sloping sides, because the walls have nothing to lean against as they bake. Level the beans with your hand so the weight is even.

For a fully baked case, bake at 200°C (180°C fan, gas mark 6) for 15 to 20 minutes, until the visible pastry edge is set and pale gold. Remove the parchment and beans carefully, then return the case to the oven for a further 5 to 8 minutes. This second bake is what turns a soggy base into a crisp, biscuit-like one. For a partially baked case, which you need for custard or frangipane fillings, stop after the first stage and brush the inside with beaten egg or melted butter to seal it.

Trimming for a Clean, Crisp Edge

There are two schools of thought on trimming, and both work. The first is to trim the overhang with scissors once the pastry is lined and chilled, leaving a 1cm lip above the rim. The second, and the one I prefer for neat edges, is to leave the overhang in place through the first bake, then run a sharp serrated knife horizontally across the rim of the hot tin. The crisp excess snaps away cleanly and leaves a perfect, level edge.

If you trim before baking, be gentle. Sawing at cold pastry drags it and encourages shrinkage. A light, decisive cut with a sharp blade is far better than a hesitant one.

Watch the exposed rim during baking. If it is colouring too quickly, cover it with thin strips of foil or a pastry ring, but keep the base uncovered so it can dry out properly.

Wholegrain Pastry: A Different Set of Rules

Wholemeal wheat, spelt and rye flours make wonderfully nutty, characterful pastry, but they behave differently. The bran particles interrupt gluten formation, so the dough is more fragile and slightly thirstier. Add an extra tablespoon of water if the dough looks dry, and handle it as little as possible.

Because wholegrain pastry has less elasticity, it can crack as you line the tin. Patch any tears with a scrap of dough pressed gently into place, then chill again. A 50/50 blend of wholemeal and white flour is a good starting point if you are new to it, and it still gives you the flavour and texture you are after.

• Rest wholegrain dough for longer, ideally an hour, to let the bran soften.
• Roll it slightly thicker, around 4mm, so it holds together.
• Bake a little more gently, around 190°C (170°C fan), as the bran browns quickly.

Cooling, Sealing, and Filling

Leave the case in its tin for 5 to 10 minutes once it comes out of the oven, then transfer it to a wire rack. Cooling in the tin any longer traps steam and softens the base. If you are not filling it straight away, store it in an airtight tin for up to two days, or freeze it for a month.

For wet fillings, brush the inside of the cooled case with melted chocolate, beaten egg white or a thin layer of warmed jam, then let it set before adding the filling. This invisible barrier keeps the pastry crisp for hours rather than minutes, and it is the difference between a tart that slices cleanly and one that collapses on the plate.