For Filling
In a saucepan over medium heat, combine the diced apples, brown sugar, cinnamon, nutmeg, all-spice, ginger, salt, vanilla extract and unsalted butter. Toss until the apples are evenly coated and cook for about 5 minutes or until the apples are slightly softened. Add the cornstarch slurry and gently stir to thicken the mixture. Remove from the heat and let it cool slightly.
Assembly and Baking:
Preheat the oven to 375° F or according to the instructions on the dough package. Line a baking sheet with parchment paper.
On a lightly floured surface, unroll the premade pie crust. Using a round cutter, cut out circles from the pie dough. You may need to gather and re-roll the dough scraps to cut out more circles. Make sure you have an even number of circles as you will need one circle of the bottom and top layer of the pie.
Arrange half the dough circle on a lined baking sheet, these will be the bottom layer of the pie. Place about a tablespoon or more of the apple pie filling in the center of the dough circles (bottom layer). Then, use a knife to cut slits in the remaining dough circles which will be the top layer.
Place the top layer dough circles on top of the filled bottom layer then use the back of a fork to press and seal the edges.
In a small bowl, whisk together the beaten egg and 1 tablespoon of milk, cream or water to create an egg wash.
Brush the top of the hand pies with the egg wash. Sprinkle a bit of coarse sugar on top for a crunchy finish.
Bake for 20 - 25 minutes or until they are golden brown and the filling is bubbly.