Preheat your oven to 350°F (175°C). Prepare your baking dish by lightly greasing it or lining it with parchment paper.

In a medium skillet, heat a tablespoon of olive oil over medium heat. Add the finely chopped onion and bell pepper and sauté for about 5-7 minutes.

In a large mixing bowl, combine the ground beef and ground Italian sausage with the sautéed vegetables. Pour in Worcestershire sauce and add minced garlic, oregano, basil, and parsley.

Fold in the Italian bread crumbs, crumbled white bread, and milk into the mixture. Add the shredded mozzarella and grated Parmesan cheese, stirring gently to combine.

Transfer the meat mixture to your prepared baking dish, shaping it into a loaf form roughly 2 inches high.

Spread a generous layer of marinara sauce over the meatloaf and sprinkle with reserved mozzarella cheese.

Bake for 60-75 minutes, or until the internal temperature reaches 160°F (70°C).

Remove the meatloaf from the oven and let it rest for 10 minutes before slicing.