To make the crust, empty the pie crust mix into a large bowl. Using a pastry blender or two knives, cut the cold butter into the mix until crumbly. Add ice cold water, one tablespoon at a time, and mix until the dough just comes together.
Split the dough in half and form each half into a round disc. Wrap tightly in plastic wrap and chill in the refrigerator for at least 1 hour.
To make the filling, combine the frozen cherries, sugar, arrowroot, and lemon juice in a medium saucepan. Heat over medium-high heat, stirring constantly, until mixture thickens and starts to bubble, about 5-6 minutes. Remove from heat and transfer to a heat-proof bowl to cool.
Preheat the oven to 375°F and line 2 baking sheets with parchment paper. Remove the dough from the refrigerator and, working with one disc at a time, roll the dough out to about ¼ inch thickness. If the dough is still crumbly, sprinkle ice cold water onto the surface and work it into the dough until it comes together.
Use a round cookie cutter to cut out circles of dough. Gather the scraps of dough and re-roll as necessary. Arrange half of the circles on the prepared baking sheet. Scoop 2 tablespoons of cherry filling onto the centers of each round.
The remaining circles will be the top crust. Use a sharp knife to cut 2 slits into the centers of the remaining circles. Use your fingers to brush cold water around the edges of each pie, then place the top crust on each and gently seal all around the edges. Bake for 28-30 minutes. Allow the hand pies to cool on the baking sheets for 10 minutes before removing.
Do not defrost the frozen cherries before using. Make sure you are using pitted cherries.
Cornstarch can be used as a 1:1 substitute for arrowroot.
If the dough becomes too difficult to work with and starts to fall apart as you are rolling and cutting your circles, refrigerate for 15 minutes. The warmer the dough gets, the harder it is to use.
I recommend using a 3.5 inch round cookie cutter for these mini pies.
I chose not to brush the tops with egg wash because I don't use eggs in my baking. If you are not allergic to eggs, you can go ahead and use egg wash to achieve a more golden color.