Set up three shallow bowls: flour in the first, beaten eggs and milk in the second, and breadcrumbs, Parmesan, garlic powder, Italian seasoning, paprika, and pepper in the third.
Unwrap and cut each mozzarella string cheese stick in half crosswise to make 32 shorter pieces.
Dip each cheese piece in flour, then egg mixture, then breadcrumb mixture, pressing firmly to coat all sides. Place on a parchment-lined baking sheet.
Repeat the egg and breadcrumb dip for a second coating, pressing firmly. This double layer prevents cheese leakage and ensures extra crunch.
Freeze the coated cheese sticks for at least 30 minutes. This crucial step firms the cheese so it melts slowly and stays inside the coating during cooking.
Preheat your air fryer to 390°F (200°C) for 3-5 minutes.
Spray the air fryer basket with cooking spray. Arrange frozen cheese sticks in a single layer with 1/2 inch space between each. Lightly spray the tops.
Air fry at 390°F (200°C) for 6-8 minutes. Flip halfway through at 4 minutes and spray the other side. Cook in batches to avoid overcrowding.
Remove immediately and serve hot with warm marinara sauce for dipping. Enjoy while the cheese is perfectly melted and gooey.