Step 1: Preheat your oven to 375°F (190°C). Grease a 9x13 inch baking dish. Cook pasta according to package directions until al dente. Drain and set aside.
Step 2: In a large skillet or Dutch oven, heat olive oil over medium-high heat. Add ground beef and cook, breaking it up with a spoon, until browned. Drain excess grease and transfer to a bowl.
Step 3: In the same skillet, add Italian sausage and cook, breaking it apart, until browned. Drain excess grease and add to the bowl with the ground beef.
Step 4: Add chopped onion and bell pepper (if using) to the skillet. Sauté for 5-7 minutes until softened. Add minced garlic and cook for another minute until fragrant.
Step 5: Return the cooked ground beef and Italian sausage to the skillet with the vegetables. Stir in the pizza sauce, diced tomatoes (undrained), Italian seasoning, salt, and pepper. Bring to a simmer and cook for 5-10 minutes, allowing flavors to meld.
Step 6: Fold the cooked pasta into the sauce mixture until evenly coated.
Step 7: Spread half of the pasta mixture into the prepared baking dish.
Step 8: Sprinkle with 1.5 cups of mozzarella cheese and arrange half of the pepperoni slices over the cheese.
Step 9: Spoon the remaining pasta mixture over the pepperoni layer.
Step 10: Top with the remaining 1.5 cups of mozzarella cheese and pepperoni. Sprinkle with grated Parmesan cheese.
Step 11: Cover loosely with aluminum foil and bake for 20 minutes.
Step 12: Remove foil and continue baking for another 10-15 minutes, or until cheese is bubbly and lightly golden brown. For extra crispiness, you can broil for the last 1-2 minutes (watch carefully!).
Step 13: Let the Meat Lovers Pizza Pasta Bake rest for 5-10 minutes before serving. Garnish with fresh basil or parsley, if desired.