Combine flour and sugar in the bowl of a food processor fitted with the dough blade.
Pulse until combined.
Add butter, a little at a time, pulsing after each addition.
Continue to pulse until butter is broken down into small pieces.
Add water.
Pulse until it forms a dough.
Divide dough into 2 portions - one 24 ounces and one 12 ounces.
Form each piece of dough into a rectangle.
Flatten slightly.
Wrap in plastic wrap.
Refrigerate for 10 minutes.
Remove 24 ounce piece from refrigerator and roll dough out on a non-stick surface (marble, parchment paper, silicone mat) that has been dusted with flour. It should be rolled to ⅛ inch thick.
Transfer dough to a 10 inch x 15 inch jelly roll pan.
Gently fit into pan, making sure there are no air bubbles.
Trim excess. (Save in case you need a little extra.) Set aside.
On a non-stick surface (marble, parchment paper, or silicone mat) roll 12 ounce piece of dough to ⅛ inch thick.
Cut into strips to make lattice.
Pour apple pie filling into bottom crust.
Lay dough strips in a lattice pattern (see photos in post above).
Pinch to seal onto bottom crust.
Refrigerate for 20-25 minutes.
While pie is chilling, heat oven to 350℉/177℃.
Make the egg wash by whisking together the egg and cream until smooth. Set aside.
Remove pie from refrigerator.
Brush with egg wash.
Bake for 40-45 minutes, or until pastry is golden brown and filling is bubbly.