Peel, core, and dice one apple; then place into a small saucepan.
Add sugar, water, lemon juice, cornstarch, cinnamon, and maple extract to saucepan and stir to coat apples with mixture. Bring mixture to a boil over medium heat, stirring frequently until the apples are soft and the liquid is thick, about 7-8 minutes.
While the apple mixture is cooking, cut the tops off the remaining four apples and hollow out the insides of each apple with a melon baller. Spoon the thickened apple mixture into the center of each apple, filling to the top.
On a flour surface, roll out the pie crust using a rolling pin. Cut the dough into ⅓ inch thick, 4-5 inch long strips. Place three strips over one apple vertically, then two horizontally. Alternate strips to create a lattice pattern. Repeat with the remaining three apples.
In a small bowl, beat egg and milk to form an egg wash. Brush mixture over pie crust, then sprinkle with sugar (if desired).
Preheat air fryer (if your model has this option) to 350℉. Line the basket with parchment paper, if using, and carefully place apples in the basket. Air fry for 15 minutes at 350℉, or until crust turns golden brown. Remove apples from air fryer, top with vanilla ice cream (if desired), and serve immediately.