In a large mixing bowl, combine the mashed bananas, egg, granulated sugar, brown sugar, melted butter, and vanilla extract. Mix well until smooth.
In a separate bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Do not overmix.
Preheat the air fryer to 320°F (160°C) for 3 minutes.
Line six silicone muffin cups or lightly grease six muffin molds that fit your air fryer basket.
Divide the batter evenly among the muffin cups, filling each about 3/4 full.
Place the muffin cups in the air fryer basket and cook at 320°F (160°C) for 15 minutes, or until a toothpick inserted into the center comes out clean.
Carefully remove the muffins from the air fryer and allow them to cool in the cups for 5 minutes before transferring to a wire rack to cool completely.