Creating Stuffed Italian Meatloaf is an enjoyable and rewarding cooking experience. Follow these simple steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Mix the Meat: In a large bowl, combine ground beef and ground pork. Mix until well incorporated.
3. Add Ingredients: Add breadcrumbs, Parmesan cheese, parsley, garlic, eggs, oregano, salt, and pepper. Mix everything by hand until just combined; avoid overmixing.
4. Prepare the Marinara: In a separate bowl, mix the marinara sauce with diced bell peppers and onion if using. Set aside.
5. Shape the Loaf: On a parchment-lined baking sheet, shape the meat mixture into a rectangular loaf, about 1 inch thick.
6. Fill with Cheese: Spread shredded mozzarella down the center of the loaf.
7. Add Marinara: Spoon a layer of the marinara mixture over the cheese, then fold the meat over to enclose the filling. Pinch the edges to seal.
8. Top with Sauce: Pour extra marinara sauce over the top of the loaf for added moisture and flavor.
9. Bake: Place the meatloaf in the preheated oven and bake for 1 hour, or until the internal temperature reaches 160°F (70°C).
10. Rest: Once baked, let it sit for 10 minutes before slicing to allow the juices to redistribute.

These easy steps will lead you to a stunning and delicious Stuffed Italian Meatloaf that everyone will love.