
Add the breadcrumbs, salt, pepper, onion powder, and Italian seasoning to a large bowl. Mix well to combine.
Add the milk, egg, garlic, and parsley to the breadcrumb mixture and stir until well combined, then let it sit for 5 minutes for the breadcrumbs to absorb the liquid.
Add the ground beef, pork, and parmesan cheese to the soaked breadcrumbs and gently mix well to combine. Shape the mixture into 16 meatballs, about 2 inches in diameter each.
Preheat the air fryer to 400°F if your model requires it.
Spray the air fryer basket with nonstick cooking spray. Place the meatballs in the air fryer, with the sides touching slightly. (Work in batches if needed, depending on the size of your air fryer.) Lightly coat the tops of the meatballs with cooking spray.
Air fry at 400°F for 10 to 12 minutes, or until the internal temperature of the meatballs reaches 160°F on an instant-read thermometer. Serve immediately.