If you’re a perfectionist or want to understand the real science of pie crust, get hold of The Pie and Pastry Bible by Rose Levy Beranbaum. She's the guru of all gurus when it comes to this stuff, and unlike me, she really knows what she's doing. I use her basic recipe but I simplify it so I can get my head around the thing. Probably not as good as hers but here it is:
Pastry for a double crust, nine inch Pie
14 Tablespoons unsalted frozen butter, divided
2¼ cups (320 grams) bleached all-purpose flour
¼ tsp + 1/8 tsp salt
¼ tsp baking Powder
5-7 Tablespoons Ice Cold Water
1 Tablespoon Apple Cider Vinegar
You can use a bowl and one of those pastry choppers--that’s how my Grandma did it-- but I use the food processor because it’s WAY easier.
Using the large holes on a cheese grater and working over a cold plate, grate a whole stick of the frozen butter. Put it in the refrigerator for 30 minutes.
Cut up the remaining butter (6 Tablespoons) into ¾” cubes. Put it in the freezer for 30 minutes.
Put the dry ingredients (flour, salt, baking powder) into the food processor. Give that a couple of whirls to mix it up.
From the refrigerator take out the grated butter, add to flour and pulse about 20 times until it resembles coarse flour.
Now add the frozen cubes of butter and pulse about 20 more times until the cubes are the size of peas.
Add 5 T of ice cold water and the tablespoon of vinegar, while pulsing the processor about 6 times.
The flour will look like damp sand. Pinch some of the sand between your fingers; it should flatten and hold together. (If it doesn’t hold together, you can add more ice water (up to 2 additional Tablespoons) and give it a couple more pulses.
Divide the “sand” into 2 equal piles. (I put the piles on large pieces of plastic wrap) Flatten into two discs; wrap each disc tightly with plastic wrap and refrigerate for 45 minutes or overnight.