Step 1: Prepare the Meatloaf Mixture

1. Preheat your oven to 350°F (175°C) and lightly grease a baking sheet or line it with parchment paper.
2. In a large mixing bowl, combine the ground beef, ground pork, Italian breadcrumbs, grated Parmesan cheese, eggs, milk, minced garlic, diced onion, chopped parsley, dried oregano, salt, and black pepper.
3. Mix the ingredients until well combined, but be careful not to overmix, as this can make the meatloaf tough. Set aside.

Step 2: Prepare the Stuffing

1. In a medium bowl, combine the shredded mozzarella, grated Parmesan, chopped spinach, chopped roasted red bell peppers (if using), thinly sliced prosciutto or salami (if using), and fresh basil.
2. Stir until the ingredients are well mixed. This filling will add flavor and moisture to the meatloaf, while also providing a beautiful layer when sliced.

Step 3: Assemble the Meatloaf Brasciole

1. Place a large sheet of parchment paper or plastic wrap on your work surface. Spread the meatloaf mixture onto the sheet, pressing it into a rectangular shape about ½ inch thick.
2. Spread the cheese and vegetable stuffing evenly over the meatloaf rectangle, leaving about a 1-inch border around the edges to prevent the filling from spilling out when you roll it.
3. Using the parchment paper or plastic wrap to help you, carefully roll the meatloaf from one short end to the other, creating a tight roll. Pinch the seams and ends to seal the roll and prevent the filling from leaking out during baking.
4. Carefully transfer the rolled meatloaf onto the prepared baking sheet, seam-side down.

Step 4: Prepare the Tomato Sauce

1. In a medium saucepan, heat the olive oil over medium heat. Add the chopped onion and cook until softened, about 3-4 minutes.
2. Add the minced garlic and cook for another 30 seconds until fragrant.
3. Stir in the tomato sauce, Italian seasoning, red pepper flakes (if using), salt, and black pepper. Bring the sauce to a simmer, then reduce the heat and let it cook for 10-15 minutes, allowing the flavors to meld.
4. Pour about half of the tomato sauce over the meatloaf roll, reserving the rest for serving.

Step 5: Bake the Meatloaf Brasciole

1. Cover the meatloaf with foil and bake in the preheated oven for 45 minutes.
2. Remove the foil and spoon some of the remaining tomato sauce over the meatloaf.
3. Continue baking, uncovered, for an additional 30 minutes, or until the internal temperature reaches 160°F (71°C) and the top is nicely browned.
4. Remove the meatloaf from the oven and let it rest for 10 minutes before slicing. This resting period allows the juices to redistribute, keeping the meatloaf moist.

Step 6: Serve and Garnish

1. Slice the Meatloaf Brasciole into thick pieces and serve with the reserved tomato sauce on the side.
2. Garnish with fresh basil or parsley for a pop of color and added flavor. Serve hot and enjoy this Italian-inspired twist on classic meatloaf!