Using a sharp knife, cut the mozzarella sticks in half width-wise.
In a shallow dish, whisk together the flour with 1/4 teaspoon kosher salt and 1/8 teaspoon black pepper.
In a second shallow dish, whisk together the eggs.
In a third shallow dish, add the breadcrumbs.
Dredge the mozzarella sticks in the flour, shaking off any excess. Dip the mozzarella sticks into the eggs then coat them in the breadcrumbs. Transfer the coated mozzarella sticks onto a plate then place them in the freezer for 30 minutes.
Preheat the air fryer to 380°F.
Coat the frozen mozzarella sticks on all sides with cooking spray then add them to the air fryer.
Air-fry the mozzarella sticks until golden brown, 5 to 7 minutes. Remove them from the air fryer and serve immediately with marinara sauce for dipping.