Peel and slice the peaches into thin wedges. Set them aside.
Roll out the puff pastry on a floured surface into an even thickness. Cut the pastry sheet into 9 equal squares.
Place a few peach slices in the center of each square. Add a sprinkle of sugar.
Fold each square into a triangle, or pull in all the edges and pinch them together to seal.
Whisk the egg in a small bowl. Brush the tops of the turnovers with the egg wash and sprinkle with extra sugar.
Place the turnovers on a parchment-lined baking sheet. Bake them at 425°F for about 15 minutes, or until they are golden brown. Allow them to cool slightly on a wire rack before serving. Enjoy!