Preheat your oven to 425°F (220°C).
Let your Pillsbury pie crust pouches sit at room temperature for about 15 minutes so they unroll smoothly without cracking.
Unroll your first pie crust and gently press it firmly against the bottom and sides of a standard 9-inch glass pie plate; flute (crimp) edges and set aside.
In a massive mixing bowl, combine your 10 cored and sliced apple wedges. Add the fresh lemon juice, white sugar, light brown sugar, all-purpose flour, cinnamon, and nutmeg.
Toss everything together thoroughly until all the apple slices are evenly coated in the sweet, spiced mixture.
Spoon the apples tightly into your crust-lined pie plate. Tip: Pack them down gently to minimize air pockets. Dot the top of the apples with your 3 tablespoons of cubed butter.
Unroll your second pie crust onto a lightly floured clean surface.
Use your favorite seasonal cookie cutters (such as leaves, stars, or apple shapes) to cut out cute dough shapes.
Layer or arrange these cutout shapes overlapping each other directly on top of the mound of apples, ensuring there are still small natural gaps for steam to vent. Alternatively, you can place a solid top crust down, cut a few center shapes out of it, and scatter extra cutout shapes around the fluted edges!
Using a pastry brush, gently brush your whisked egg over the top crust and cutouts. This gives the pie an incredible glossy, golden finish.
Place your pie onto a baking sheet (to catch any bubbling juices) and bake at 425°F for 15 to 20 minutes.
Reduce the oven temperature to 350°F (175°C). To prevent your pretty cookie cutouts and crust edges from burning, loosely tent the pie with a sheet of aluminum foil. Bake for another 30 to 40 minutes, or until the apples are fork-tender and the juices are bubbling thick.
As tempting as it is to cut into a hot pie, let it cool completely on a wire rack for at least 2 hours. This allows the flour and natural apple starches to cool and set the filling so your slices hold the shape.