Prepare the Dough: In a mixing bowl, combine 2 ½ cups of all-purpose flour, 1 teaspoon of sugar, and 1 teaspoon of salt. Cut in 1 cup of cold unsalted butter until the mixture resembles coarse crumbs. Gradually add ice water, 1 tablespoon at a time, mixing until the dough comes together. Shape the dough into two discs, wrap them in plastic wrap, and refrigerate for at least 1 hour.

Make the Apple Filling: While the dough chills, peel, core, and slice about 6 medium apples into thin wedges. In a large bowl, toss the apple slices with ¾ cup of brown sugar, 1 teaspoon of cinnamon, ¼ teaspoon of nutmeg, and 1 tablespoon of lemon juice. Add 2 tablespoons of cornstarch to help thicken the filling. Let this mixture sit for about 10 minutes, allowing the flavors to meld.

Roll Out the Dough: Preheat your oven to 425°F (220°C). Once the dough has chilled, take one disc out of the refrigerator and roll it out on a floured surface into a 12-inch circle. Carefully transfer the rolled dough to a 9-inch pie pan, pressing it gently along the bottom and sides. Trim any excess dough hanging over the edges for a neat finish.

Fill the Pie: Spoon the apple filling into the prepared crust, ensuring an even distribution. Pile it slightly higher in the center to create a lovely dome shape.

Create the Lattice Crust: Roll out the second dough disc into a similar size and slice it into strips about ¾ inch wide. Create a lattice pattern over the filling by laying half the strips vertically, then weaving the remaining strips horizontally through those. Trim and crimp the edges to seal the pie and create a decorative finish.

Apply the Egg Wash: In a small bowl, whisk one egg with a tablespoon of water to create an egg wash. Gently brush the lattice and edges with this mixture.

Add Black Sugar: Sprinkle a generous amount of black sugar over the lattice and crust to add that eerie touch.

Bake the Pie: Place the pie in the preheated oven and bake for 15 minutes at 425°F (220°C). Then, reduce the temperature to 350°F (175°C) and continue baking for an additional 30-35 minutes.

Cool and Serve: Once baked, remove the pie from the oven and let it cool on a wire rack for at least 2 hours before serving warm or at room temperature.