Cut the butter into 1/2 tablespoon slices and place in the freezer while you prepare the rest of your ingredients. Measure out 3/4 cup water and place into the cup a few ice cubes. Set aside.
Whisk together the flour, corn starch, salt, and baking powder.
Add 8 tablespoons of the chilled butter to the flour mix, toss, then use two knives or a pastry cutter to cut the butter in until it's like sand with small pieces of gravel. Toss the remaining 6 tablespoons of chilled butter with the flour but don't cut in.
Transfer the flour mix and butter to a gallon Ziploc bag, press out the air, seal, and use a rolling pin to flatten, shake the bag slightly, then flatten again. Don't shake, place the sealed bag into the freezer and chill for 15-30 minutes.
Pour the chilled flour and butter into a bowl, sprinkle on the apple cider vinegar and 5 tablespoons of ice water. Fold to incorporate. Sprinkle on 2 more tablespoons of ice water, fold, and repeat adding 1 tablespoon of water until you can press the dough between your fingers and it sticks together but doesn't seem sticky or wet.
Turn the dough onto a countertop or workplace. Lightly press into a mound. Divide into a 60/40 ratio. Press each into a round and flatten to 1" thick. Wrap each disc with plastic wrap. It will be crumbly but that's okay. Refrigerate for 1 hour or overnight.
Lay a piece of parchment paper on the countertop. Sprinkle a little flour on the paper. Unwrap the larger dough disc onto the parchment. Press together to incorporate any loose dough into the sides. Sprinkle a little flour on top of the dough then lay a piece of parchment paper on top. Use a straight rolling pin on the parchment paper and roll out to desired thickness or diameter. Generally a pie crust is slightly less than 1/4" thick and about 11-12" round for a 9" pie pan.
You can trim the edges at this point or turn the rolled dough into your pie pan and trim after. Press pieces of dough onto any cracks or splits.
Repeat with the smaller piece. Place on filled pie pan or cut into lattice strips. Bake according to specific pie recipe.