Cut out the center of refrigerated flaky biscuit dough to make a donut shape. You can also shape the outside of the dough using cookie cutters (hearts, stars, etc.) if you want. Dip the doughnuts in melted butter and cook them in batches in the air fryer at 330˚F for 8-10 minutes, flipping them over halfway through cooking. Coat the donuts with glaze or butter and cinnamon sugar.