On a floured work surface, roll out one pastry sheet using a floured rolling pin to about ¼-inch thick (this only took me about 4 back and forth rolls total – two vertically, two horizontally). Slice rolled out pastry sheet into nine rectangles then transfer them to the parchment paper lined baking sheet (these are the bottoms of the pop-tarts). Repeat process of rolling and slicing with the second pastry sheet. Using a pastry brush, brush the edges of the bottom rectangles (the ones on the parchment paper lined baking sheet) with the egg wash then top ¼-⅓ cup of cherry mixture in the middle of the rectangle. Place the top rectangles over the cherry filling, lining them up the edges (best you can ha!) then crimp the edges together with a fork. Continue until all nine pop-tarts are sealed then slice 2-3 slits in the tops using a sharp knife so the pop-tarts can vent while baking. Brush the tops of the pop-tarts with egg wash then top with coarse sugar. Chill the pop-tarts in the refrigerator for about 30 minutes.