Classic Apple Pie with Flaky Crust

1. Make the pie dough. In a large bowl, whisk together flour, sugar, and salt. Add cold butter and cut it in with a pastry cutter until you have pea sized pieces plus a few flatter, almond sized shards. Those bigger bits are future flakes.
2. Add water gradually. Mix 6 tablespoons ice water with the vinegar (if using). Drizzle in a few tablespoons at a time, tossing with a fork, until the dough holds together when you squeeze it. It should look shaggy, not wet. Add more water only if needed, 1 tablespoon at a time.
3. Divide and chill. Turn dough onto the counter, press into a ball without kneading, then divide into two disks. Wrap tightly and refrigerate at least 1 hour (or up to 2 days).
4. Macerate the apples. In a big bowl, toss sliced apples with granulated sugar, brown sugar, lemon juice, cinnamon, nutmeg, allspice (if using), and salt. Let sit 30 to 45 minutes until the apples release a good amount of juice.
5. Preheat and prep your pan. About 20 minutes before you are ready to assemble, preheat the oven to 425°F. Set a sheet pan on the middle rack to preheat too. Hot pan, crisp bottom, everyone wins.
6. Reduce the juice for a sliceable filling. Set a colander over a saucepan and drain the apples, catching the liquid. Simmer the liquid over medium heat for 5 to 8 minutes until reduced and slightly syrupy. Let cool for a few minutes.
7. Finish the filling. Toss the apples with cornstarch, flour, vanilla, and the reduced syrup until evenly coated.
8. Roll the bottom crust. On a lightly floured surface, roll one disk into a 12 inch circle. Ease into a 9 inch pie dish, lifting the edges as needed so you do not stretch the dough. Chill the lined pie dish while you roll the top crust.
9. Roll the top crust. Roll the second disk into a 12 inch circle. If the dough warms up, slide it onto a sheet pan and chill 10 minutes. Cold dough is your best friend here.
10. Assemble. Fill the pie with apples, mounding slightly in the center. Dot with the 2 tablespoons butter pieces.
11. Top and seal. Lay the top crust over the filling. Trim excess to about 1 inch overhang, fold under, and crimp. Cut 5 to 6 vents in the top so steam can escape.
12. Chill the assembled pie. Refrigerate the whole pie for 15 minutes. This keeps the butter cold and helps the bottom crust start strong.
13. Egg wash. Whisk egg with milk. Brush over the top crust, avoiding heavy puddles at the crimp. Sprinkle coarse sugar if using.
14. Bake. Place pie on the preheated sheet pan. Bake at 425°F for 20 minutes, then reduce to 375°F and bake 40 to 50 minutes more, until deeply golden and the filling bubbles through the vents. If the edges brown too fast, loosely tent with foil.
15. Cool completely. Let the pie cool on a rack for at least 3 hours before slicing. This is the difference between clean slices and apple lava.

Optional upgrade: If you want extra crisp bottom crust, bake the pie in the lower third of the oven for the final 20 minutes.