Preheat air fryer to 350
Grease and flour two 7" pans
Mash banana and add lemon juice, set aside.
1/2 cup mashed banana, 1/2 tsp lemon juice
Beat together butter, brown and white sugar until combined with hand mixer
1/4 cup packed brown sugar, 1/3 cup white sugar, 4 tbsp softened butter
Add in egg and vanilla and mix on high until light & fluffy (almost the texture of frosting). Set aside.
1 egg, 1/2 tsp vanilla
In a separate bowl, combine flour, baking soda, cinnamon and salt in a medium bowl.
1 cup all purpose flour, 1/2 tsp baking soda, 1/2 tsp baking powder, 1/4 tsp salt, 1/2 tsp cinnamon
Alternate adding flour mixture and buttermilk to sugar/egg batter. Mix on medium setting just until combined
1/2 cup buttermilk
Fold in bananas and pour into pans
Sprinkle walnuts on top of both cakes
2 tbsp chopped walnuts
Put into air fryer and reduce heat to 300 degrees. Bake 20 minutes or until toothpick inserted in center comes out clean. (do not overbake - check at 15-17 min)
Remove from oven and place in freezer for 45 minutes. This helps keep the cake extra moist!