Preheat your air fryer to 350°F (175°C). Roll out the crescent roll dough until smooth and pinch the seams tightly to form a solid sheet. Cut the dough into 8 equal squares.

Place 1 teaspoon of Nutella in the center of each dough square. Spread the Nutella carefully to avoid overfilling.

Fold the edges of each dough square over the Nutella filling, pinching them closed to create pockets. Roll each pocket into a ball shape.

Brush the exterior of each Nutella ball with the beaten egg for a golden-brown crust.

Carefully place the Nutella balls in the air fryer and cook for 6-8 minutes, flipping them halfway through.

Remove the Nutella balls and brush with melted butter. Roll in the cinnamon-sugar mixture and let cool slightly before serving.