Making Apple Pie With Puff Pastry is straightforward if you follow these clear steps:

1. Preheat Oven: Preheat your oven to 425°F (220°C).
2. Prepare Apples: In a large mixing bowl, combine the sliced apples, granulated sugar, flour, lemon juice, cinnamon, nutmeg (if using), and salt. Toss until the apples are evenly coated.
3. Line the Pan: Roll out one sheet of puff pastry to fit your pie dish. Place it in the dish and trim the excess overhang.
4. Fill the Pie: Pour the apple mixture into the lined pie crust, ensuring it is evenly distributed.
5. Top with Puff Pastry: Roll out the second sheet of puff pastry and place it on top of the apple filling. Cut slits in the pastry to create vent holes.
6. Trim and Crimp Edges: Trim any excess pastry from the edges and use your fingers or a fork to crimp the edges for a decorative finish.
7. Prepare Egg Wash: In a small bowl, whisk together the egg and milk. Brush this mixture over the top of the pastry for a golden finish.
8. Bake the Pie: Place the pie on a baking sheet to catch any drips, then bake in the preheated oven for 30-35 minutes or until the pastry is golden brown and the apple filling is bubbly.
9. Cool the Pie: Once baked, remove the pie from the oven and let it cool for 15-20 minutes before slicing. This cooling time allows the filling to set slightly.

These straightforward steps will guide you in creating a truly incredible Apple Pie With Puff Pastry that will impress anyone lucky enough to enjoy a slice.