Add the cold, diced butter to the flour mixture. Use a pastry cutter or your hands to work the butter into the flour until the mixture resembles coarse crumbs with pea-sized pieces of butter.

Divide the dough in half and shape each half into a disk. Wrap each disk in plastic wrap and refrigerate for at least 1 hour (or up to 2 days). Chilling the dough allows the butter to firm up, making it easier to roll out.

On a lightly floured surface, roll out one disk of dough to about 1/8-inch thickness. Carefully transfer the rolled-out dough to a 9-inch pie dish, pressing it gently into the bottom and sides. Trim any excess dough, leaving about a 1/2-inch overhang.

If making a double-crust pie, repeat the rolling process with the second disk of dough. For a single-crust pie, crimp the edges as desired, and proceed with your pie recipe.

If pre-baking (blind baking) the crust, prick the bottom with a fork, line with parchment paper, and fill with pie weights or dried beans. Bake at 375°F (190°C) for 15-20 minutes until the edges are golden. Remove the weights and parchment and bake for an additional 5-7 minutes until the bottom is lightly browned.