Heat a large skillet over medium-high heat. Add the ground beef and onions, cooking for about 4 minutes. Stir in the diced bell pepper and cook for another 5 minutes, until the beef is browned. Drain any excess grease.
1 pound ground beef, ½ cup yellow onion, 1 small green bell pepper
Reduce the heat to medium and pour in the beef broth, scraping up any browned bits from the pan. Stir in the garlic, Worcestershire sauce, and Italian seasoning. Cook for 1 minute, then add the marinara sauce and stir well. Let the sauce simmer, partially covered, while you cook the pasta.
½ cup beef broth, 3 cloves garlic, 2 teaspoons Worcestershire sauce, 32 ounces marinara sauce, 1 tablespoon Italian Seasoning
Boil the penne pasta for 1 minute less than the al dente time listed on the package. Drain and set aside.
¾ pound penne pasta
Reduce the heat on the sauce to low, then stir in the grated Parmesan cheese. Add the cooked pasta and mix everything together.
¼ cup Parmesan cheese
Transfer the mixture to the prepared casserole dish. Sprinkle with shredded mozzarella and top with pepperoni slices.
2 ½ cups mozzarella, 25 slices pepperoni
Bake in the air fryer at 375°F (190°C), uncovered, for 10 minutes or until the cheese is melted and slightly golden.
Serve warm and enjoy!