Start by preheating your oven to 375°F (190°C) and prepare a baking sheet by lightly greasing it or lining it with parchment paper. Dust your work surface with flour and roll out the pizza dough into a large rectangle, roughly 12x15 inches. The dough should be about ¼ inch thick to ensure a good balance of crust and filling.

Spread the marinara sauce evenly over the rolled-out dough. If you prefer a drier Stromboli, you can skip this step. Next, layer the shredded mozzarella (1 cup), grated Parmesan (¼ cup), pepperoni (10 slices), salami (10 slices), and chicken (10 slices). Sprinkle the mixture with dried oregano (1 tsp), garlic powder (1 tsp), and red pepper flakes (1 tsp) if using. Finish with the fresh basil (¼ cup), spreading it evenly over the fillings.

Carefully roll the dough tightly starting from one of the shorter edges, ensuring the filling remains inside. Once rolled, pinch the edges to seal it properly. Place the seam-side down on the prepared baking sheet to prevent it from unrolling.

Brush the top of the Stromboli with the beaten egg for that golden finish. Sprinkle it with the remaining grated Parmesan (1 tbsp) and Italian seasoning (1 tsp) to enhance the flavor.

Bake the Stromboli in the preheated oven for 25-30 minutes or until the crust is a beautiful golden brown. Keep an eye on it towards the end, as oven temperatures may vary.

Once baked, let your Stromboli cool for about 5-10 minutes before slicing it into 1-inch pieces. Serve it warm with the optional marinara sauce on the side for dipping!