Preheat oven to 425°F (220°C). Lightly grease a muffin tin.
Roll out the pie crusts and cut 12 circles using a cookie cutter or glass to fit the muffin tin wells.
Place each dough circle into the muffin tin to form a mini pie base.
In a bowl, combine diced apples, both sugars, flour, cinnamon, nutmeg, lemon juice, and vanilla extract.
Spoon the apple filling evenly into the dough cups.
Cut additional dough circles or lattice strips to cover the tops of the mini pies as desired.
Brush the tops with beaten egg for a golden finish.
Bake for 16–18 minutes, or until the crust is golden brown.
Cool in the pan for 10 minutes before transferring to a wire rack.