Creating an incredible Apple Slab Pie is easier than you might think. Follow these simple steps:

1. Preheat the Oven: Set your oven to 425°F (220°C) to ensure it’s hot and ready for baking.
2. Prepare the Apples: In a large bowl, combine the sliced apples, granulated sugar, brown sugar, lemon juice, cinnamon, nutmeg, and cornstarch. Toss until the apples are well coated. Set aside for about 10 minutes.
3. Roll Out the Crust: If using refrigerated pie crusts, roll out one crust to fit a 13×18-inch baking sheet. Press the crust into the bottom of the sheet, allowing some to hang over the edges.
4. Fill the Pie: Pour the prepared apple mixture into the crust in an even layer. Dot the filling with small pieces of butter for added richness.
5. Prepare the Lattice Top: Roll out the second pie crust and cut it into strips. Weave these strips over the apple filling to create a lattice pattern. Trim any excess dough and fold the edges under, crimping them to seal.
6. Egg Wash: In a small bowl, whisk together the egg and milk. Brush this mixture over the lattice crust for a golden finish.
7. Bake: Place the slab pie in the preheated oven and bake for 45-50 minutes, or until the crust is golden brown and the filling is bubbling.
8. Cool Down: Once baked, remove from the oven and let it cool for 20-30 minutes before slicing. This allows the filling to set properly.
9. Slice and Serve: Cut the pie into squares or rectangles, serving it warm or at room temperature.

These steps will guide you in creating an incredible dessert that will wow your guests and family alike!