For the crust:
For the filing:
1. In a food processor, combine the flour, sugar, and salt. Process few seconds until combined. Add cold, cubed butter and pulse until crumbs are formed. Gradually add ice water and pulse until dough is formed.
2. Divide the dough into 2 pieces, flatten into disks, wrap in plastic wrap and refrigerate for 1 hour.
3. Meanwhile make the filling: in a large bowl place sliced apples, add sugar, cornstarch, salt, nutmeg, cinnamon and lemon juice, stir well.
4. Preheat oven to 400F (200C).
5. On a floured work surface roll out one piece of dough into a circle 11-12-inches (28-30cm) in diameter. Carefully place the dough into a 9-inch (22-23cm) pie dish, press the edges and trim the excess dough. Add the apple mixture and refrigerate while you working with the second dough.
6. Roll out the second dough into a circle 10 inches (25cm) in diameter. Using a pastry wheel or knife cut 10 strips. Arrange lattice pattern: Lay out 5 strips on top of the filling, with. Fold back every other strip. Add a strip perpendicular to the parallel strips. Unfold and repeat with the other parallel strips until the lattice pattern is ready. Press the edges and trim the excess dough.
7.From the leftover dough cut leaves (optional).
8. Beat egg and 1 teaspoon of water. Brush the crust.
9. Bake for 20 minutes, then add a pie crust shield or aluminum foil on top of the pie and bake 30-40 minutes more.
10. Remove from the oven and let cool for at least 3 hours before serving.