Transfer unsalted butter in a ramekin and place on the Air Fryer tray in the middle cooking chamber, near the rotisserie catch. Melt butter while pre-heating the Air Fryer.
Place into preheated air fryer. Test doneness after 8 minutes. Insert a toothpick at the middle of the brownie bites. If it comes out clean, remove the Air Fryer tray. If the toothpick is wet, continue Air Frying for another 1 or 2 minutes.