1. Preheat the oven to 170°C (degree Celsius), grease and line cake pan with baking paper. Or for easy serving, bake them in individual cupcake case.
2. Beat butter, shaved gula melaka and vanilla using an electric mixer until light and fluffy. Beat in eggs one at a time until well mixed.
3. Next fold in half portion of the sifted flours (flour, baking soda and salt) till well mixed, add in mashed banana and stir till combined with the remaining flours.
4. Lastly stir in Kahula and chopped walnuts, mixed till combined.
5. Pour batter into prepared cake pan, top with sliced banana, walnuts and generous amount of shaved gula melaka.
6. Bake in preheated oven for approximately 50 minutes until a skewer in the middle comes out clean. For cupcake size, bake for approximately 20 - 25 minutes.