Use ½ teaspoon of butter to grease 2 ramekins that will fit into your air fryer.
Combine apples, water, sugar, cinnamon, and salt in a small bowl. Spoon into the prepared ramekins and cover with aluminum foil.
Air fry at 350°F (175°C) for 15 minutes.
Mix together the rolled oats, flour, brown sugar, and melted butter in a small bowl until it resembles rough gravel.
When the 15 minutes is up, remove the foil from the top of the ramekins. Spoon the topping onto the top of the apple mixture in each ramekin. Air fry for another 6 minutes to crisp up the topping.
Notes
Tuck the tinfoil around the ramekins tightly so that the tinfoil doesn’t blow off during cooking. This will keep the apples from drying out.
Cut the apples similar in size so they all cook at the same rate.
Select apples that are firm and slightly tart for the best flavor and texture. Varieties like Granny Smith, Honeycrisp, or Fuji work well. Granny Smith apples hold up well to cooking and give a slight tartness to go along with the sweet.
Make sure the topping is golden brown and crispy before removing it from the air fryer. You can cook it a bit longer if needed.
Feel free to customize the topping with nuts like chopped almonds or pecans for extra crunch and flavor.
All air fryers have different wattage and may cook at different rates. You may need to adjust the time or temp for the best results.