Why is my pastry greasy and leaking butter?

Fat in pastry is supposed to melt, but it is supposed to melt *inside* a structure that has already begun to set, so the space it leaves becomes a flake or a short crumb. If the dough is warm going in, or the oven is not hot enough to set the flour and protein quickly, the fat liquefies and runs out before anything is holding it. What you get is a pool on the tray, a pale greasy pastry and a case that has lost the fat that was meant to make it short.

What you'll need

• A freezer with space for a tray (optional)
• An oven thermometer (optional)

Step by step

1. Check the oven temperature for real.Pastry wants a hot start — most shortcrust bakes at 190–200°C, puff hotter still. An oven running twenty degrees low is a very common cause of butter leaking, and the dial will not tell you. See `check-oven-temperature`.
2. Chill the shaped pastry properly before it bakes.Not the dough — the finished, lined, trimmed case or the cut shapes. Twenty minutes in the freezer, or an hour in the fridge. It should go into the oven properly cold.
3. Keep your hands off it.Hands are at 34°C and butter softens at around 30°C. Use a rolling pin, a scraper and the fridge, and handle the dough as little and as briefly as you can.
4. Work in a cool kitchen, or make it cooler.Chill the bowl, the flour and the worktop if you can. Pastry made in a hot summer kitchen next to a preheating oven is fighting a losing battle.
5. Check the fat ratio.Classic shortcrust is half fat to flour by weight; sweet pastries go higher. Above roughly two-thirds fat to flour there is more butter than the flour can hold and some will always leak.
6. Look at how the fat was incorporated.Fat rubbed in until it disappears completely gives a fine, sandy, greasy-prone pastry. Leaving some pieces the size of small peas gives flakiness and holds the fat better. Rub in less than feels finished.
7. Bake on a preheated tray.A hot baking sheet under a tart tin drives heat into the base immediately, setting it before the fat runs. It also helps the soggy-bottom problem — see `fix-a-soggy-pastry-base`.

Tips

• Frozen grated butter is an excellent way to get evenly distributed cold fat without warming it with your fingers.
• Half butter, half lard or vegetable shortening makes a more forgiving shortcrust: the higher-melting fat holds up longer while the butter provides the flavour.
• If the pastry has softened halfway through lining a tin, stop and put the whole thing in the fridge for fifteen minutes. Carrying on with soft pastry never ends well.
• A little leakage from a very rich sweet pastry is normal and is why they are baked on a lined tray rather than directly on a shelf.

Common mistakes

• Turning the oven down because the pastry is browning — The first ten minutes at full heat are what set the structure. Turn it down after that if you must, not at the start.
• Kneading the pastry smooth — It warms the fat and develops gluten in one action, giving pastry that is both greasy and tough.

If it doesn't work