Unroll the crescent roll dough on a lightly floured surface and pinch the seams together to form a solid sheet, then cut into 24 equal squares.

Place about 1 teaspoon of Nutella in the center of each dough square, keeping the filling away from the edges.

Fold the corners of each square up over the Nutella, pinch the seams tightly to seal, then roll gently between your hands to form a smooth ball with no cracks.

Brush each dough ball lightly with the beaten egg, coating all sides.

Preheat the air fryer to 350°F.

Place the Nutella balls in a single layer in the air fryer basket, leaving space between each ball.

Air fry at 350°F for 6 to 8 minutes, flipping halfway through, until the balls are puffed and golden brown.

While the balls cook, stir the sugar and cinnamon together in a shallow bowl.

Remove the hot Nutella balls from the air fryer, brush immediately with melted butter, then roll each ball in the cinnamon sugar to coat.

Let the Nutella balls cool for 5 minutes before serving to allow the centers to set slightly.