Preheat oven to 350 degrees then coat broiler pan or baking sheet with cooking spray.
Place large skillet over medium heat then add olive oil. Add onion and bell pepper then cook until softened, about 4 minutes. Add garlic and continue cooking for an additional 30 seconds. Remove from heat, stir in Worcestershire sauce then set aside to cool.
In a large mixing bowl, add cooled onion mixture, ground beef, Italian sausage, basil, oregano, parsley, salt, pepper and beaten eggs. Mix by hand until ingredients are evenly incorporated, then add grated Parmesan and breadcrumbs. Gently mix until combined
Transfer mixture to prepared pan then shape into loaf about 5" wide and 2"–3" high with a slight divot in the top to hold the marinara in place. Spoon marinara sauce into the divot spread as close to edges as possible.
Bake 45–55 minutes or until internal temperature reaches 155 degrees in the thickest part of the meatloaf. Remove from oven then sprinkle with mozzarella cheese and return to bake for about 5 minutes, until the cheese is nicely melted. Remove from oven and allow meatloaf to rest for 5 minutes. Sprinkle with fresh chopped parsley, slice and serve with a little grated Parmesan and some extra marinara sauce on the side.