Preheat the oven to 450°F.
Remove pie crust from packaging and allow to sit on counter for about 30 minutes to come to room temperature. Unroll one crust on a lightly floured surface, maintaining the thickness it came in the package (do not roll thinner). Use a 6-inch bowl as a template; set it upside down on the crust and cut out two circles from the dough. Gently gather up the extra scraps and roll them out just enough to cut two additional circles (you may even need to do one at a time to keep the dough thick enough).
Place three crust circles onto a baking sheet sprayed with non-stick cooking spray.
Scoop a couple tablespoons of the blueberry pie filling into the center of each crust.
If desired, place a small piece of butter over the pie filling (this isn’t necessary, it adds creaminess to the finished hand pie).
Use a fork to beat the egg lightly.
Brush a bit of the egg wash around the edge of the circle to help the sides seal. Fold the pie crust in half to form a crescent shape. Press down (work from the outer edge in) and then crimp with your fingers or a fork to seal the edges.
Brush the exposed sides of the hand pie with the egg wash. Sprinkle desired amount of coarse sugar over the egg wash.
Bake for 10-12 minutes or until the pies are golden brown and the crust is crispy. (The filling does not need to be cooked so we’re really just cooking the crust here.)