In a bowl, mix together the risotto, Parmesan cheese, and egg.
Make 20 equal-sized balls from the mixture.
Insert a mozzarella cube in the center of each ball.
With your fingers, smooth the risotto mixture to cover the mozzarella.
In a shallow dish, place the breadcrumbs.
Coat the balls with breadcrumbs evenly.
Grease the Air Fryer Basket with cooking spray and then slide inside.
Adjust the temperature of Air Fryer to 390 °F to preheat for 5 minutes.
After preheating, arrange half of the balls into the greased Air Fryer Basket in a single layer.
Slide the basket into Air Fryer and set the time for 10 minutes.
After cooking time is finished, remove the balls from Air Fryer and place onto a platter.
Repeat with the remaining balls.