For the Crust:
Prepare the crust: In a large bowl, combine the flour, salt, and sugar (if making a homemade crust). Cut the cold butter into small pieces and incorporate it into the flour mixture. Using a pastry cutter or your hands, work the butter into the flour until the mixture resembles coarse crumbs with pea-sized pieces of butter.
Add ice water: Gradually add ice water, a tablespoon at a time, until the dough begins to come together. Make sure not to overwork the dough.
Chill the dough: Divide the dough into two equal portions, shape each into a disk, wrap them in plastic wrap, and refrigerate for at least 30 minutes.
Roll out the dough: After the dough has chilled, roll out one disk on a floured surface to fit into a 9-inch pie dish. Transfer the rolled dough into the pie dish and trim any excess dough from the edges. Set the crust in the refrigerator while you prepare the filling
For the Filling:
Prepare the apples: Peel, core, and slice the apples into thin, even slices. Transfer them to a large mixing bowl.
Mix the filling ingredients: In the same bowl, add granulated sugar, brown sugar, all-purpose flour, cinnamon, nutmeg, vanilla extract, lemon juice, and cornstarch. Toss the apples gently to coat them evenly with the mixture.
Assemble the pie: Take the prepared pie crust from the refrigerator. Spoon the apple mixture into the crust, mounding it slightly in the center for a beautiful shape.
Top with the second crust: Roll out the second disk of dough and place it over the apples. Trim any excess dough, then pinch the edges of both crusts together to seal. You can crimp the edges with your fingers or a fork for a decorative look. Make a few small slits in the top crust to allow steam to escape during baking..
Brush with egg wash: Beat the egg and brush it over the top crust to give it a golden, shiny finish. Sprinkle the top with a tablespoon of sugar for a sweet, crisp crust.
Baking the Pie:
Allow the pie to cool for at least 2 hours before slicing, giving the filling time to set. For an extra indulgent treat, serve with a scoop of vanilla ice cream or a dollop of whipped cream!.