Start by combining the sugar, flour, baking powder, salt, nutmeg, and cinnamon, in a small bowl.
Mix in the bananas and eggs.
Mix in the yogurt melted butter and mix well.
Mix everything well, until it's all well blended.
Fold in the walnuts.
Divide the batter into prepared muffin tins, either the silicone cups or regular paper tins (it depends on if you have the air fryer muffin tin or not)
I use an ice cream scoop, which makes it easy to scoop the batter into the muffin tins.
Fill the muffin tins 2/3 full.
Place the muffin tin or the silicone cups into the air fryer basket, and set the temperature for 320 degrees for 12 minutes.
Remove from the air fryer basket.