Make the crust: In a large bowl, whisk together the flour, salt, baking powder, and sugar.
Add the cubed butter and work it in with your fingers or a pastry cutter. Don’t overwork the mixture. There should be larger chunks of butter among the smaller ones.
Add the vinegar and 4 tablespoons of water. Toss to combine. Continue adding water one tablespoon at a time to make a chunky, cohesive mixture. The mixture should hold together when you squeeze a handful of it.
Divide the dough into two pieces, one containing about 60% of the dough and the other containing about 40%. Wrap each individually in plastic wrap and refrigerate until cold (at least 30 minutes and up to an hour).
When chilled, remove the larger piece of dough from the refrigerator and roll it out on a lightly floured surface to a rectangle approximately 11x15 inches. Place on a baking sheet and return to the refrigerator while mixing the filling.
Start preheating the oven to 350 degrees.
Make the filling: In a small bowl, combine the sugar, flour, cinnamon, nutmeg, and salt. Place the apples in a large mixing bowl and sprinkle with the lemon juice. Pour over the sugar mixture and toss until evenly coated.
Remove the baking sheet from the refrigerator and place the apple mixture evenly on top leaving at least a one-inch border all around.
Roll the remaining dough into a rectangle approximately 9x13. Lay the top crust over the apples and seal the edges of the two crusts bringing the bottom crust up and over the top crust and folding them together.
Brush the entire top and edges of the crust with milk or cream. Sprinkle evenly with your choice of sugar. Slash the top a few times to allow for venting.
Bake for 1 hour. If the crust starts to get too brown before the end of the baking time, cover loosely with a sheet of aluminum foil and continue baking.
Remove pie from the oven and allow to cool for 30 minutes before serving.
Serve with ice cream if desired.