In a large skillet over medium heat, cook the beef and onion until the beef is browned and the onion is softened, 6-7 minutes. Drain excess fat if needed.
1 pound ground beef, 1 small onion
Stir in the cooked rice, tomato sauce, Worcestershire, garlic powder, Italian seasoning, salt, pepper, and half of the cheese. Mix until well combined.
1 cup cooked rice, 8 ounces tomato sauce, 1 teaspoon Worcestershire sauce, 1 ½ teaspoons garlic powder, 1 teaspoon Italian seasoning, ½ teaspoon salt, ½ teaspoon black pepper, 1 cup shredded mozzarella
Spoon the filling evenly into the peppers.
4 bell peppers
Arrange peppers in the air fryer basket, cook in batches if needed. Air fry at 360° F for 10 minutes, until the peppers are tender.
Sprinkle the remaining cheese over the tops and air fry for another 2 minutes, or until the cheese is fully melted.
Let cool slightly before serving