Steps
1. Preheat your oven to 180°C (350°F) or prepare a microwave-safe mug.
2. In a bowl, mash the ripe banana until smooth.
3. Add sugar, vegetable oil, and milk to the mashed banana and mix well.
4. In a separate bowl, combine wheat flour, custard powder, baking powder, and salt.
5. Gradually add the dry ingredients to the wet mixture, stirring until just combined.
6. Pour the batter into a small greased cake pan or microwave-safe mug.
7. Bake in the oven for 20-25 minutes or microwave on high for 2-3 minutes until a toothpick inserted comes out clean.
8. Allow to cool slightly before serving.