Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
Roll out the pizza dough on a floured surface into a large rectangle, about 10x14 inches.
In a large bowl, mix together the sausage, ground beef, pepperoni, bell pepper, onion, mozzarella, cheddar, Parmesan, Italian seasoning, and garlic powder.
Evenly spread the filling mixture down the center of the dough, leaving a 1-inch border along the edges.
Carefully fold in the sides of the dough, then roll it up like a jelly roll, sealing the edges.
Place seam-side down on the prepared baking sheet and brush with the beaten egg.
Bake for 25–30 minutes or until golden brown and cooked through.
Let it rest for 5–10 minutes before slicing. Serve with warm marinara sauce on the side.
