Preheat oven to 180 degrees. Grease and flour a small loaf pan and set aside.

In a bowl, combine the mashed banana and butter till well combined.

Add the soda and salt and mix.

Add in the sugar, egg and vanilla and mix well.

Finally add in the flour and whisk without lumps. Fold in the walnuts.

Pour into the prepared pan and flatten surface. Bake for 40 to 45 minutes till skewer comes out clean. Allow to cool in the tin for 10 minutes.

Flip onto cooling rack and cool completely before slicing and serving!