Cut the Butter (12 tablespoon) and Vegetable Shortening (8 tablespoon) into smaller pieces, if you are not using a food processor.
Pour the Gluten-Free Pie Crust Mix (1 package) into a large mixing bowl, or a food processor fitted with a steel blade, and add the butter and shortening. Pulse or use a pastry blender or two knives to cut butter and shortening in.
Cut or pulse until the mixture resembles coarse sand.
Sprinkle with Water (6 tablespoon).
Gently mix until the dough just comes together, add an additional 2 tablespoons of ice water, if needed.
Once the dough has all come together. Divide it into two equal parts.
Flatten each piece into disks.
Wrap each disk tightly in plastic wrap, and refrigerate for 1 hour.
Peel and cut Granny Smith Apple (4 pound) into 1/4-inch slices and place in a large bowl.
In a bowl, add Granulated Sugar (1/2 cup), Salt (1/4 teaspoon), Ground Nutmeg (1/4 teaspoon), Ground Cinnamon (1/4 teaspoon) and zest of a Lemon (1).
Slice the zested lemon in half and add Lemon (1 tablespoon) to the bowl.
Mix the the sugar mixture together.
Add the sugar mixture to the bowl of apples and mix thoroughly.
Preheat your oven to 425 degrees F (220 degrees C).
Remove one disk from the refrigerator. Place it between two pieces of plastic wrap, and roll out the bottom crust into a 12-inch circle.
Remove the top layer of plastic wrap.
Invert and press dough into a 9-inch pie pan. Remove remaining plastic wrap.
Press dough into pie pan.
Pour apple mixture into pie shell.
Remove the other disk of dough from the refridgerator. Between two pieces of plastic wrap, roll the dough into a 12-inch circle.
Remove the top layer of plastic wrap, and place the top crust over the filliing. Remove the final piece of plastic wrap from the top crust.
Trim dough edges, leaving 1/2-inch overhang.
Tuck overhanging dough beneath itself. Flute or crimp with a fork to seal.
Cut three slits in top crust. Place pie in freezer for 10 minutes if dough is very soft and sticky.
Brush the top crust lightly with the Egg (1) white or milk.
Sprinkle with Granulated Sugar (1 tablespoon).
Bake on center rack for 25 minutes at 425 degrees F (220 degrees C).
Reduce temperature to 375 degrees F (190 degrees C), place a baking sheet on lower rack and bake for 30-35 minutes more, until crust is golden brown and juices are bubbling.
Remove from oven and cool on wire rack for at least 1 hour before serving.