The solution: Relax your dough. It's tempting to work homemade dough into a cohesive ball, but this over-develops gluten. The dough should just hold together when squeezed in the palm of your hand, with bits of fat visible throughout. Form the dough into a disk, wrap, and chill at least 20 minutes—this lets the gluten unwind. To form the pie shell, gently roll the dough into a circle larger than the pan, at least 12 inches, and then trim and flute. Stretching a too-small circle to fit the pan will stretch the gluten. Chill the pie shell before filling. (If you feel you've stretched purchased dough, chill it, too; this will relax the gluten and help prevent shrinkage.) The fat, still solid from the fridge, will melt and steam in the oven, creating delicious flaky layers.