Once the pie dough has rested, remove one disc from the refrigerator and use a rolling pin to roll the disc into a 10 1/2-inch circle on a lightly floured surface. Fit onto a 9-inch pie plate. Transfer to the refrigerator to chill while you make the filling.
In a medium bowl, whisk together 3/4 cup granulated sugar, "tightly packed" 1/2 cup dark brown sugar, 2 tablespoons all-purpose flour, 1/2 teaspoon ground cinnamon, 1/8 teaspoon ground nutmeg, and a pinch of kosher salt until well combined.
Place 6 cups cored and sliced apples in a large bowl. Sprinkle the dry ingredients (from the 1st step) over the apples and toss until evenly coated. Spoon into the prepared pie shell in the pie plate and cover loosely with plastic wrap; transfer to the refrigerator to chill while you roll out and work with the second disc of pie dough for the lid.
Roll out the second disc into a 10 1/2-inch circle for the pie lid; carefully transfer to a parchment paper-lined sheet pan and place in the freezer to chill for 10 minutes, before using cookie cutters to stamp out the pattern of your choice across the circle. Once satisfied with your design, transfer back to the freezer to chill for another 10 minutes to firm up the lid.
Once the lid is firm, remove the pie crust base from the refrigerator. Carefully transfer the pie crust lid on top of the fruit, centering the lid accordingly. Use kitchen shears to trim any dough overhang from both the lid and the crust, using the edge of the pie plate as a guide for trimming. Cover loosely with plastic wrap and transfer to the freezer to chill for at least 24 hours before baking.