1Wash and dry the apples; do not peel them.
2Using a teaspoon or small knife, carefully core each apple without cutting all the way through. Set aside the apple pieces to add to the topping.
3In a small bowl, mix the melted salted butter with 1 teaspoon of ground cinnamon.
4Using a pastry brush, brush the outside and inside cavity of each apple with the cinnamon butter. Set aside.
5In a medium bowl, combine rolled oats, chopped pecans, brown sugar, 1 teaspoon of ground cinnamon, and 2 tablespoons of unsalted butter. If you have reserved apple pieces, chop them finely and add to the mixture. Mix well.
6Divide the oat mixture evenly between the two apples, pressing it into the cavities.
7Pour 1/2 cup of water into the bottom of the air fryer basket.
8Place the apples carefully in the basket and cook in the air fryer at 175°C (350°F) for 13–15 minutes; check after 10 minutes for doneness.
9Serve warm, optionally with vanilla ice cream, caramel sauce, or whipped cream.