In a bowl mash the bananas and add the sugar, oil, milk and vanilla. Whisk to combine everything.
Place a sieve on top and add the dry ingredients - flour (reserving about a tbsp of it), baking powder, baking soda and salt. Sieve them together.
Combine to form a cake batter. And when you could still see some bits of flour left in the batter that is when you add the walnuts but do remember to coat the walnuts with the reserved flour and then add.
Fold to form the cake batter and then transfer it to a pre-lined 6 inch cake pan. Smoothen the top and sprinkle more chopped walnuts on top if you like.
Pre-heat the air fryer at 180°C for 3-5 mins.
Place the cake pan in the pre-heated air fryer and bake at 180° for 20 mins.
After 20 mins open the air fryer, place an aluminium foil on top of the cake and bake for another 5-8 mins or until a skewer inserted in the centre comes out clean.
Once baked, carefully remove the cake pan. Let the cake sit in the cake pan for another 3-4 mins then invert on to a wire rack to cool completely before slicing and serving.
To make it dairy free use almond or oat milk in place of regular milk.
Make sure to use ripe bananas. If it is not ripe you can keep it in a rice bag overnight or simply microwave it in a burst of 30 seconds to quickly ripen the bananas.
If the bananas are too ripe then it would mean too much moisture in the batter so you might need additional 1-2 mins to bake the cake.
Ensure to chop the walnuts well and coat it with flour so that you get an even dispersement of the same once baked.
Cover the banana cake with an aluminium foil midway through baking to avoid over-browning on top.
Always pre-heat your air fryer for atleast 3-5 mins irrespective of the recipe that you are making.
As a general rule of thumb, when it comes to baking ensure that you are not over-mixing the batter and also are lining your cake pan well before baking.