Preheat oven to 375 degrees. Pull out pie dough & allow to come to room temperature.
Peel, core and dice granny smith apples.
Into a bowl add all of your dry ingredients (flour, brown sugar, granulated sugar, nutmeg and cinnamon). Whisk to combine.
Add apples into a large bowl & toss in lemon juice. Allow to sit for a few minutes.
Next add your dry ingredients into the apple bowl. Toss to coat apples completely in sugar mixture. Let sit for 5-10 minutes, you will notice a wet coating will begin to form.
Lightly grease your pie plate. Roll out your dough so that it is about 12 inches in length.
Place 1 pie dough into pie plate.
Add your apple filling into the pie plate. Drizzle any cinnamon mixture remaining in bowl on top & top with cubed butter.
Top pie with 2nd pie dough. You can get creative here by using a pastry roller to cut out strips of dough and creating lattice on your pie. You can braid the stripes, fold them into a pattern or just place the dough on top & cut in a few "air vents".
Crack egg into a small bowl. Whisk the egg so that it is completely mixed. Using a pastry brush, "paint" egg wash onto top of pie dough.
Bake pie in oven for 45-50 minutes.
Allow to cool for 15 minutes, serve & enjoy!