Separate the biscuits and cut out the center using a small biscuit cutter.
Place the butter in a small microwave safe bowl and microwave for 15-30 seconds, until melted. Stir in the vanilla extract.
Add the cinnamon sugar and salt to a shallow bowl. Brush the tops of the donuts with a thin layer of melted butter. Dip the top of each donut into cinnamon sugar. Brush a thin layer of butter over the air fryer basket to keep the donuts from sticking. Working in batches, place donuts in the air fryer basket in a single layer. Air fry for 3 minutes, flip and cook 2-3 more minutes.
Remove the donuts from the air fryer and brush the bottoms with butter. Dip in cinnamon sugar to coat. Serve warm.
Hot Chocolate Donuts
Place the hot chocolate mix and granulated sugar in a shallow bowl. Mix to combine. Use a fork to break up any chocolate clumps.
After cooking, brush the donuts entirely with butter and cover with hot chocolate mix.
Drizzle chocolate syrup over each donut and top with mini marshmallows.
Maple Bacon Donuts
Melt butter in a sauce pan over medium heat with maple syrup. Once melted, remove from heat and whisk in confectioners' sugar. If the icing hardens, you can place it back over the stove.
Dip the top of each donut in the maple icing, then sprinkle with diced bacon.