Using a 3 1/2" heart-shaped cookie cutter, you should get 8-10 pies from 1 box of crusts. Cut as many shapes as you can get rerolling scraps as needed.
Mix together egg and milk to make an egg wash.
Line a baking sheet with parchment paper. Place half of the hearts on prepared pan(s).
Use egg wash to wet the edges of the hearts. Place a small amount of the pie filling in the center of each.
Make a small x cut in the center of the remaining half of the hearts. Place an x heart on top of each filled heart and press and crimp edges.
Brush the sealed pie with egg wash and dust with sparkling sugar.
Bake for 14-16 minutes until crust is browned.
Notes
You can store any of the mini cherry pies you manage to keep your family from eating right away for about 4 days. Just cool and refrigerate in an airtight container. Reheat before serving. Delicious with vanilla ice cream or homemade whipped cream!