Preheat the air fryer. Set it to 380°F (193°C). Give the basket a light spray with oil to prevent sticking.

Mix the wet and dry binders first. In a large bowl, combine breadcrumbs, milk, grated onion, egg, garlic, parsley, Italian seasoning, salt, pepper, and red pepper flakes. Stir until the breadcrumbs are evenly moistened.

Add the turkey last. Gently mix in the ground turkey with your hands or a fork until just combined.

Don’t overwork it—stop as soon as everything looks evenly distributed.

Form the meatballs. Scoop about 1 1/2 tablespoons per meatball (roughly golf-ball size). Lightly oil your hands if the mixture is sticky. You should get 16–18 meatballs.

Arrange in the basket. Place meatballs in a single layer with slight space between them.

Lightly spray the tops with oil for better browning. Work in batches if needed.

Air fry. Cook for 10–12 minutes, shaking the basket or turning the meatballs halfway through. They’re done when the outsides are golden and the internal temperature hits 165°F (74°C).

Rest briefly. Let the meatballs sit for 2–3 minutes to redistribute juices.

Toss with warm marinara, sprinkle Parmesan, and serve however you like.