First, make the pie crust dough. In a large bowl, add the flour and salt, stir to combine. Use a box grater to shred the cold butter. This is the secret to the best flaky pie crust! Add the cold butter to the flour mixture and mix together with your clean hands. The mixture will be crumbly, resembling small pebbles.
This should only take a couple minutes. Part of the goal is to touch/mix the pie crust dough the least amount possible, as this will result in the flakiest crust. Overworking the dough can make it gummy or crunchy like a giant cracker.
Add the ice water and again use your clean hands to mix until a dough ball forms. Press the dough together, you do not need to knead the dough. Divide in two and form small disks. Wrap in plastic wrap and refrigerate until you are ready to use.
Then make the filling. Peel and core the apples. Cut into small pieces. In a medium sauce pan, add the sugar, butter, vanilla extract and cinnamon. Cook over medium heat until melted. Add the apple pieces to the pan and cook for 5 minutes until they begin to soften some.
In a small bowl or cup, stir together the cornstarch and water into a slurry. Pour this into the pan and continue to cook for 1-2 minutes. The liquid should begin to thicken.
Lightly flour your counter and rolling pin. Remove the dough from the refrigerator and unwrap from the plastic wrap. Use the rolling pin to press down and roll out the dough. If it sticks to the pin or counter dust more flour onto these surfaces.
Once I have the pie crust dough the size I need, I will gently roll it around my rolling pin and then transfer this over my prepared, meaning buttered, pie pan. Then unroll it from the pin.
Add the filling, cover the top with the second rolled out dough and then crimp the edges. Pierce the center a few times with a sharp knife, this allows steam to escape as it bakes.
Cover the edges with aluminum foil or a pie shield. Bake at 400°F for 25 minutes. Remove the foil edges and reduce the oven temperate to 375°F. Bake for another 30 minutes.