A slumped wall and a cracked base are two different faults with two different causes, and they are cured differently. Walls shrink when the dough contracts: gluten has developed, or the dough has not rested. Cracks appear when the dough is too dry or rolled unevenly. You can tell which is which by looking.
Six causes below, in order of how often they turn up. The recipe is not part of it — the same formula gives a different result depending on how the dough is mixed and chilled.
One: gluten developed
Shortcrust should not be elastic. The moment flour meets liquid and the dough is worked, the proteins in the flour form a gluten network — and that network contracts when heated, pulling the wall down and inward.
The tell: the wall has sunk evenly all the way round and has visibly thickened, as though the dough has drawn itself in. The base is intact.
The cure is the order of mixing. Butter is rubbed into the flour to a crumb first, and only then is liquid added — the fat coats the flour particles and physically stops the proteins joining. As soon as the dough comes together, stop: an extra thirty seconds in a stand mixer costs half a centimetre of wall height.
Two: the dough did not rest
Gluten is under tension after mixing regardless, even when you work carefully. Resting in the fridge lets it relax and lets the butter firm up again.
Two hours is the minimum, overnight is better. Dough rolled twenty minutes after mixing will shrink no matter how cold you get it before baking: chilling stops the butter but does not release the tension.
A second rest, once the dough is in the ring, is compulsory too — 30 to 40 minutes in the cold. Lining the ring tightens the dough again, especially if you pressed it in with your fingers.
Three: the butter melted
The whole point of shortcrust is that solid particles of fat separate layers of flour. If the butter melts — during mixing, during rolling, or simply from warm hands — it soaks into the flour, and the pastry stops being short and becomes dense.
The tell: the wall has not just sunk, it has flowed, there is a small pool of fat at the base, and the surface after baking looks greasy and shiny.
The working temperature for rolling is no higher than 16 °C. In a warm kitchen, roll between sheets of parchment and return the dough to the cold every few minutes.
Four: uneven thickness
This is where cracks come from. Where the dough is thinner, it bakes and dries faster than the patch next to it — that creates stress, and the sheet tears.
The tell is distinctive: the crack runs from the centre of the base to the edge, or exactly along the line where base becomes wall, which is where the change in thickness is greatest.
Roll on guide rails or between strips of a fixed height, 2.5 to 3 mm for a tart. Almost nobody holds an even thickness by eye, and half a millimetre of difference is already enough to tear.
Five: the dough was stretched into the ring
If the sheet is smaller than the ring and you pull it to make it fit, the stretched dough will contract again in the oven. That is pure mechanics, and no amount of resting overrides it.
The tell: the wall has not dropped evenly but in patches, wherever you pulled hardest. Often one side is noticeably lower than the other.
Line the ring with an excess, press the dough into the base and up the walls, and trim the surplus with a knife along the top edge — after the piece has had time in the cold.
Six: the oven
A tart shell bakes at 160–170 °C. Higher heat sets the surface quickly while the inside is still expanding — the same tear again.
A perforated ring on a perforated mat works better than weights: steam escapes through the holes, the wall holds its own shape and the base comes out flat. With a solid ring and no weights the base domes almost every time.
Choosing between weights and perforation, and when to lift the weights, is its own subject — covered in the piece on blind baking. How three different shortcrusts behave under identical conditions is covered in the comparison of sablée, sucrée and brisée.
A short fault chart
| What you see | Cause |
|---|---|
| Wall sunk evenly and thickened | Gluten developed, or no resting |
| Wall flowed, fat pooled at the base | Butter melted before the oven |
| Wall lower in patches | Dough stretched when lining |
| Crack from centre to edge | Uneven rolling thickness |
| Base domed | Neither weights nor perforation |
Working with tart bases from mixing to assembly is covered across the shortcrust masterclasses.