What all of these have in common is some form of crust or topping, a universally loved treat that almost always depends on a fair amount of fat — usually butter — to make it light, flaky, and delicious. (But check out the Vegan Piecrust on page 710.) What distinguishes pies and tarts from cobblers and crisps is the composition of the crust, how it is formed, and whether it’s on top or on bottom.
A crust can make or break a pie or tart. I’m here to tell you that you can make a really good crust your first time out, and you’ll improve quickly and steadily.
I routinely use my food processor to mix the dough for crusts, and I recommend you do too. You can mix the dough by hand, of course, pinching the butter with flour between your fingers, or using various utensils like a pastry blender or two forks. However you do it, the idea is to get small bits of fat coated in flour, which will make for a flaky and light crust. The dough should be handled minimally, because you don’t want gluten to develop, as it does in bread dough; for crusts you want tenderness, not chew.
Once you make a dough, let it rest in the refrigerator (or even the freezer, but not too long — you want to chill it, not freeze it) to relax the gluten and to firm up the fat. Relaxing the gluten will make rolling easier and chilling the fat will result in flakiness in the oven.