Preheat your oven to 425°F. Grease a 12-count muffin pan or two 6-count muffin pans with cooking spray.
2. Roll out the dough until it is ¼-inch thick. Using a 4-inch cookie cutter, cut out as many circles as you can. Re-roll the dough and cut out additional circles until you have a total of 12.
3. Arrange each circle in a muffin tin cup, pressing it down and up the edges. Keep any dough scraps for the top lattice or decorations.
4. Fill each cup until nearly full, about ¼ cup, with cherry pie filling.
5. Use the remaining dough to create a top crust to cover each pie. To make a lattice crust, use a knife or pizza cutter to cut out thin strips of dough, then lace together to form a lattice.
6. Brush the tops of the pies with the egg wash, then sprinkle them with sanding sugar if desired.
7. Bake until golden brown, about 20 to 25 minutes.
8. Remove from the oven and let cool completely in the muffin tin. Using a sharp knife, run it around the edges of each pie to help release them, then serve.