Combine flour, onion powder, garlic salt and paprika in a shallow bowl. Season with pepper. Whisk eggs in a separate shallow bowl. Place breadcrumbs in a separate shallow bowl.
Cut mozzarella block in half crossways. Then cut each in half horizontally to form 4 thin pieces. Cut each piece into 5 sticks. Dip mozzarella sticks in flour mixture to coat. Shake off excess. Working in batches, coat mozzarella sticks in egg mixture then in breadcrumbs. Repeat crumbing process to double crumb. Spray the chips with oil after double crumbing.
Preheat air fryer to 200°C for 2 minutes. Working in 2 batches, cook mozzarella sticks in air fryer for 4 minutes or until golden. Stand for 2 minutes, then transfer to a board. Top with basil and serve with pesto.
Double crumbing ensures that the cheese doesn’t ooze out of the crumb during cooking.