Blend the peeled bananas, cocoa, sugar and milk together in a mixer.
Add okara and mix in.
Soak the egg over hot water until it is warm to touch, and whisk to a cream-like consistency.
Add half of the whisked egg to the mixture from step 2, then mix the rest in, making sure the bubbles remain. Add walnuts if available.
Pour the mixture into a pound cake pan lined with baking paper, and bake in the oven for 40-45 minutes at 350°F/180°C. All done.
Story Behind this Recipe
I tried making this many times, adjusting the ingredients and amounts. This is the most delicious version.
It's best if the bananas are ripe and starting to darken. If the bananas are not ripe enough, it won't be very sweet, so increase the amount of sugar. If the bananas are very sweet, you don't need sugar.