Dice 1 small onion and 1 bell pepper relatively finely.
Heat 1 Tablespoon oil in a skillet over medium heat. Sauté diced onion and pepper until the onions are translucent and everything is softened.
Set aside 1 cups marinara sauce and 1 cups shredded mozzarella cheese.
Put 1 lb. lean ground beef, 1 lb. Italian sausage, 1 teaspoon Worcestershire sauce, ½ teaspoon garlic powder, 1 teaspoon oregano, 2 large eggs, 1 cup Italian bread crumbs, ½ cup Parmesan cheese, 1 cups shredded mozzarella cheese, 1 cups marinara sauce, and the cooked pepper and onion mixture in a large mixing bowl. Use your hands to mix until uniform.
Form into a meatloaf in the center of a 9x13-inch pan. Top with remaining 1 cups marinara sauce.
Bake for 50 minutes. Sprinkle with remaining 1 cups shredded mozzarella cheese and bake 10 more minutes or until the cheese is melted and the center of the meatloaf registers at least 160°F on a meat thermometer.