01 - Preheat the air fryer to 350°F for 3 minutes.
02 - Slightly flatten each refrigerated biscuit with your hands.
03 - Place approximately 1 teaspoon of chocolate-hazelnut spread in the center of each flattened biscuit.
04 - Fold the dough over the filling, pinching the edges to seal thoroughly and shaping gently into a ball.
05 - Lightly brush the exterior of each donut ball with melted butter.
06 - Place the prepared dough balls in the air fryer basket in a single layer, working in batches if necessary.
07 - Air fry at 350°F for 7 to 8 minutes, or until golden brown and puffed.
08 - While warm, roll each donut in granulated sugar mixed with cinnamon or use plain sugar as preferred.
09 - Allow to cool slightly before serving, as the interior filling will be hot.