Line and spray or lightly oil a 6-inch round cake pan.
In a large bowl, whisk together flour, cinnamon, nutmeg, baking soda, and salt.
In a separate bowl, mash the banana (I do it quickly in a blender) and then mix in the eggs, sugar, milk, yogurt, oil and vanilla extract.
Add wet ingredients to the dry, stirring until just combined.
Pour batter into prepared pan, and sprinkle chopped walnuts on top.
Preheat air fryer to 310F / 150C, place the pan inside the Air Fryer basket and bake for about 35 minutes or until a skewer inserted into the middle omes out clean.
Remove banana bread from air fryer and place on a wire rack (srill in the pan) to cool for about 20 minutes before slicing and serving,