Preheat air fryer to 380°F (193°C) for about 3 minutes if recommended by your model.
Pat chicken thighs thoroughly dry with paper towels.
Combine ¼ cup Parmesan, garlic powder, paprika, Italian seasoning, onion powder, salt, and pepper.
Lightly rub chicken with olive oil.
Season the underside of the thighs.
Turn skin-side up and gently press the remaining seasoning over the skin.
Arrange chicken in the air fryer basket skin-side down without overlapping.
Air fry for approximately 10 minutes.
Flip the thighs skin-side up.
Continue cooking for approximately 10–14 minutes.
Check the thickest part with an instant-read thermometer. Chicken must reach at least 165°F (74°C) without touching the bone.
Meanwhile, combine melted butter, minced fresh garlic, remaining Parmesan, and parsley.
Transfer cooked chicken to a plate.
Apply a small amount of garlic-Parmesan finishing butter to each thigh.
Rest for 5 minutes.
Serve with optional lemon wedges.