Creating the Tremendous Cheesy Pepperoni Stromboli is simple with these clear steps:

1. Preheat Your Oven: Start by preheating your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Prepare the Dough: Roll out the pizza dough on a lightly floured surface into a rectangle, about 12×16 inches, keeping it approximately ¼ inch thick.
3. Add the Fillings: Spread the shredded mozzarella cheese evenly over the dough, leaving a small border around the edges. Layer the sliced pepperoni on top and sprinkle with grated Parmesan cheese, Italian seasoning, garlic powder, and red pepper flakes if using.
4. Roll It Up: Carefully roll the dough tightly from one end to the other, ensuring the filling stays inside. Pinch the seams to seal well and tuck in the ends to prevent leakage. Transfer to the baking sheet.
5. Apply Egg Wash: Beat the egg in a small bowl and brush it over the Stromboli for a golden crust. Make a few slits on top to allow steam to escape.
6. Bake: Place the Stromboli in the preheated oven and bake for 25-30 minutes or until golden brown and cooked through.
7. Cool & Slice: Once baked, remove from the oven and let it cool for about 10 minutes before slicing. Serve with warm marinara sauce on the side for dipping.

By following these straightforward steps, you’ll be able to create an amazing Tremendous Cheesy Pepperoni Stromboli that will be the star of your meal!