Place the frozen cherries, sugar, cornstarch, lemon juice, butter, vanilla extract, and salt inside a medium saucepan over medium heat. Stir frequently until the mixture comes to a boil.
Once boiling, reduce the heat and simmer for 10 minutes to thicken the mixture, stirring occasionally, until you have a thick cherry filling with large pieces of cherries.
Remove it from the heat and let it cool down to room temperature.
Make the hand pies:
Remove the refrigerated pie dough from the refrigerator and let it sit on the countertop for about 10 minutes to come to room temperature.This helps the dough become more pliable and easier to work with.
Unroll the pie dough on a lightly floured surface. Roll it out a little, without sacrificing much of the thickness, to about ¼ inch. Then, with your favorite cookie cutter shapes, cut out the pie dough into as many shapes as you can. Make sure you end up with an even number.
Place half of the cut pie dough shapes on the parchment. Spoon a few spoonfuls of cherry filling in the middle of the hand pies, leaving about ½-inch around the edges to seal the ends.
Place a second piece of dough on top of the bottom, making sure to line it up around the edges. Use a fork to seal and crimp the edges all around the hand pies.
Chill:
Refrigerate the hand pies for 30 minutes. This helps the fat in the pie dough set so that the hand pies have the right golden texture when baked.
Bake:
Preheat oven to 400ºF (200ºC) with the top oven rack positioned in the middle of the oven.
Remove the hand pies from the fridge and cut a small X-shaped slit on the top of each one. Whisk an eggwhite and the water in a small bowl and brush each cherry hand pie with the egg wash and sprinkle a little coarse sugar on top.
Bake for 16 to 18 minutes, until the tops are golden and some of the cherry juices bubble through the center. Remove from the oven and let the hand pies cool down completely before serving.
Notes
Fresh cherries: remove the pits from 3 cups of cherries. Follow the recipe as noted.
Homemade dough: use your favorite pie dough recipe which yields enough dough to make a standard pie, with a top and bottom.