Preheat the oven to 375 degrees Fahrenheit. Line 2 baking sheets with parchment paper or silicone mats.
Using gentle force with a rolling pin, roll out the dough onto a well-floured surface until it's about 1/8 inch thick. Start from the center of the disk and work your way out in all directions, turning the dough with your hands as you go.
Use a 2.75 or 3-inch round biscuit cutter (or something else round, like a jar) to cut rounds out of the dough. 1 disk will yield 24 circles. If you need to re-roll the scraps to get to 24, that is perfectly fine.
Place the rounds on the baking sheet. Fill every other round with 1 tablespoon of the peach-mango mixture. Run finger around the edges of each round with the egg wash. Place an empty round on top of the peach filled round. Press the outsides down with a fork to seal the rounds together. Repeat with the remaining rounds.
Brush the egg wash on top of the sealed mini pies. Sprinkle tops with coarse sugar. Cut two small lines at the top with a paring knife.
Bake the pies for 30-35 minutes, or until golden brown. Remove from the oven and let them cool slightly. Repeat the process with remaining disk of dough.