I made the Blackberry And Apple Pie from Domestic Goddess and followed the pastry recipe exactly. It started to come together in the food processor so I squished it into a ball and rested it into the fridge. When I came to roll it there wasn't enough to cover the dish and instead of rolling out smoothly it cracked into lots of little pieces and couldn't be rescued. The more I tried to re-roll it the worse it got. Where did I go wrong? And if this happens again is there anything I can do to rescue the pastry once it has started to break up on the initial attempt at rolling out?
Nigella's Blackberry And Apple Pie (from HOW TO BE A DOMESTIC GODDESS) has a crust that is made with the addition of a little finely ground cornmeal. This makes the pie crust slightly more crisp. If the pastry is cracking when it is being rolled out then there are two possible reasons. The first is that the dough was very cold when it was rolled. If the dough has been chilled for a long time then it can be difficult to roll and may crack, so if there has been a long chilling time you may need to remove the discs of dough from the fridge 15-20 minutes before rolling, or if already rolling then let the dough stand, loosely covered with clingfilm (plastic wrap) for 10 minutes. You can always chill the assembled pie before baking.
It is also possible that not enough water was added to the dough when it was mixed. Sometimes in a food processor or mixer it can be easy to over-process the dough and it will bind together with less water, but the dough will be dry and difficult to handle. Unfortunately it is difficult to fix a dough that is too dry but it may help to roll the dough between two sheets of baking parchment (parchment paper) as it will prevent the dough clinging to the rolling pin and tearing or cracking as much. When adding the water it is best to pulse the dough 2-3 times after each addition of water and then switch the machine off and carefully (avoiding the sharp blade if using a food processor) pinch a little together with your fingers. The dough should come together fairly easily and feel soft but not wet. If you are not sure then process the flour, cormmeal and fats together until they resemble sandy porridge then tip this mixture into a bowl and add the liquid by hand, using a palette knife or metal spatula to mix. After adding half of the water pinch a little of the dough and feel if it is coming together easily or not. If not then continue to add the water a tablespoon at a time, mixing and checking the dough between each addition.