Preheat oven to 425 degrees F. Lightly grease an extra large baking sheet; set aside. On a lightly floured surface, unroll each package of crescent-roll dough. Separate dough into individual triangles. Place half the dough triangles on the prepared baking sheet. Place about 1 tablespoon of the pepperoni-cheese mixture in the center of each triangle. In a small bowl, stir together egg and water. Brush edges of triangles with some of the egg mixture. Top with remaining triangles. Press triangle edges together to seal. Brush dough with egg mixture. Fold short edges of the dough triangles up, forming a hat brim. Prick the dough a few times with the tines of a fork.
If desired, sprinkle with additional Parmesan cheese, Italian seasoning, and/or crushed red pepper. Cut reserved pieces of pepperoni into small stars, crescent moons, and/or small diamonds. Press onto dough for decoration. Bake in the preheated oven for 8 to 10 minutes or until golden. Serve warm with pizza sauce, if desired. Makes 8 calzones.