Preheat oven to 400°F. Line a sheet pan with parchment and sprinkle with cornmeal.
Lightly flour your work surface. Stretch or roll the dough into a 12x16-inch rectangle.
Brush the dough with olive oil. Spread a thin layer of pizza sauce, leaving a 1-inch border.
Layer provolone, mozzarella, ham, and pepperoni evenly over the dough.
Sprinkle Parmesan, Italian seasoning, garlic powder, and red pepper flakes over the filling.
Roll up from a long side into a tight log. Pinch the seam and ends to seal well.
Set the stromboli seam-side down on the pan. Cut 4–5 small slits on top for steam.
Brush the top with beaten egg. Sprinkle a pinch of Italian seasoning if you like.
Bake 22–25 minutes, until deep golden and the center is hot and melty.
Rest 10 minutes. Slice into 1-inch pieces and serve with warmed sauce for dipping.