Divide the butter into two parts, 9 tablespoons and 5 tablespoons. Cut the butter into 3/4-inch cubes. Wrap each portion of butter with plastic wrap. Refrigerate the larger amount and freeze the smaller amount for at least 30 minutes. Meanwhile, make the flour mixture.
Place the flour, salt, and optional baking powder in a resealable gallon-size freezer bag and freeze for at least 30 minutes.
Place the flour mixture in a food processor with the metal blade and process for a few seconds to combine. Set the bag aside.
Add the larger amount of butter cubes to the flour and process for about 20 seconds or until the mixture resembles course meal. Add the remaining frozen butter cubes and pulse until all the frozen butter is the size of peas. (Toss with a fork to see it better).
Add the 5 tablespoons of ice water and the vinegar and pulse 6 times. Pinch a small amount of the mixture together between your fingers. If it does not hold together, add half the remaining water and pulse 3 times. Try pinching the mixture again. If necessary, add the remaining water, pulsing 3 times to incorporate it. The mixture will be in particles and will not hold together without being pinched.
Divide the crust mixture in half at this point (for top and bottom crusts), place each portion in a plastic bag.
Holding both ends of the bag opening with your fingers, knead the mixture by alternately pressing it, from the outside of the bag, with the knuckles and heels of your hand until the mixture holds together in one piece and feels slightly stretchy when pulled.
Separately wrap doughs with plastic wrap, flatten into discs, and refrigerate for at least 45 minutes, or overnight. Pie dough can be stored refrigerated, up to 2 days; frozen, up to 3 months.