Lay the biscuits on a cutting board and roll each into a larger, thinner circle.
Slice the apples thin so they cook through in the short cook time.
In a small bowl, stir together the cinnamon and sugar.
Place an apple slice in the center of each dough round and add about a tablespoon of the cinnamon sugar.
Wrap the dough into a sealed bundle, pinching the edges tightly so the filling won't leak.
Lightly spray the air fryer basket with oil and add the bundles in a single layer (work in batches if needed).
Air fry at 350°F for 5 to 7 minutes, until golden and puffed.
Let cool just enough to handle, then dip each donut in melted butter.
Roll in the remaining cinnamon-sugar mixture until coated.
Plate, serve warm, and enjoy.