Defrost frozen dough overnight in the refrigerator. Preheat oven to 350 degrees F (175 degrees C) Lightly greased, large baking sheet, set aside. Roll dough into an approximately 12x18 inch rectangle. Brush dough lightly with olive oil. Sprinkle with Italian seasoning and onion flakes. Layer with pepperoni to within a half inch of the edges. Top with mozzarella cheese. Roll dough like a jelly roll and seal seam, and edges with some of the beaten egg, place on pan seam side down, brush the top of the bread with beaten egg. Bake in the preheated oven 30 minutes, or until golden brown. Slice into about 1" slices serve immediately.