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. Wrap tightly in plastic wrap and chill in the refrigerator for at least 1 hour.
To make the filling, combine all filling ingredients in a large bowl. Stir well to incorporate. Set aside until ready to use.
Preheat the oven to 425°F and grease 1-2 standard muffin tins. Remove the dough from the refrigerator and roll out to about ½ inch thickness. If the dough is still crumbly, sprinkle ice cold water onto the surface and work it into the dough with your hands until it comes together. Use a small round cookie cutter to cut rounds out of the dough. Gather the scraps of dough and re-roll as necessary.
Transfer each round to the muffin tin and use your hands to press the dough down into each muffin cup, pushing down in the centers to form a cup. Scoop one tablespoonful of filling into each cup. Bake for 18-20 minutes, or until the crust is slightly golden. Allow to cool completely in the muffin tin before removing and serving.
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.
Feel free to use any leftover dough to cut shapes or a lattice design for the tops of the pies. Otherwise, you may also wrap tightly and freeze for up to 6 months.