Wash apples and decide how you will be slicing; feel free to peel or don't.
Melt butter in a large mixing bowl and add sugar, cinnamon, and vanilla. Stir to combine.
Stir apples into butter mixture, ensuring all slices are coated.
Preheat air fryer for 5 minutes at 400°F.
Give air fryer basket a spritz of oil and spread apples in a single layer. You might need to work in batches.
Sprinkle extra cinnamon on apples if you like them with lots of spice.
Make sure you have a drip tray underneath the air fryer basket if you want to catch the drips.
Bake for 10-12 minutes depending on the thickness of the slices and how crispy you want them. I found 10 minutes worked for the thinner slices and 12 for the thicker ones.
Repeat until all apples are cooked.
Take apples out of air fryer and cool for 5 minutes before enjoying.
Notes
Select apple varieties that are crisp and retain shape when baked, such as Granny Smith, Honeycrisp, Pink Lady, or Gala.
Store in the fridge and reheat as desired. Also tastes great cold!
Perfect on their own, stirred into oatmeal, or over vanilla ice cream.