3-2-1 pie crust (flaky, all-butter)

This is the magic ratio: 3 parts flour to 2 parts butter to 1 part water, by weight. Master this basic ratio and you can riff on it. Technique is what separates an okay pie crust from a flaky one, so here we use a food processor to keep everything cold and avoid overworking the butter. We also make heavy use of putting the dough back into the fridge or freezer to make sure everything remains cold.