Lightly grease a small air fryer-safe dish or silicone mould.
Mash the ripe banana in a bowl until smooth, then add the rolled oats and mix well.
Press the oat and banana mixture firmly into an even layer in the prepared dish.
Place the dish in the air fryer and cook at 350°F (about 175–180°C) for 15 minutes, until the base is set.
While the base cooks, core and thinly slice the apple.
Remove the dish from the air fryer and arrange the apple slices on top of the oat base in a slightly overlapping layer.
In a clean bowl, whisk together the eggs, milk and honey until smooth.
Pour the egg mixture evenly over the apples and base.
Return the dish to the air fryer and cook at 365°F (about 185°C) for about 20 minutes, until the custard is set and lightly golden.
Let the bake cool for a few minutes before slicing and serving warm.