Pre-heat air fryer to 350° F
Mix the dry ingredients first in a bowl: oats, flour, brown sugar, salt and cinnamon.
Add the melted butter and combine well until topping is crumbly.
Combine chopped apples with lemon juice, cinnamon, nutmeg and sugar.
Divide the apple mix evenly between 6-4 oz ramekins.
Cover each ramekin with aluminum foil, and place in air fryer (size of air fryer will determine how many ramekins fit at a time).
Cook in air fryer for 15 minutes.
Remove ramekins from air fryer and remover aluminum foil. Crumble the oat topping evenly over the apples.
Cook uncovered for an additional 5 minutes or until apple filling is bubbling and oat topping is golden brown.
Serve warm with ice cream, whipped cream or caramel sauce if desired.