1 large very ripe banana (approximately125g/4Β½oz peeled weight), mashed with a fork
250g/9oz sweet potato, finely grated
1 tsp bicarbonate of soda
50²µ/1ΒΎ΄Η³ϊ cocoa powder, sifted
oil, for greasing
200g/7oz self-raising flour
100²µ/3Β½΄Η³ϊ butter, cubed
3 large free-range eggs, beaten
100ml/3Β½fl oz semi-skimmed milk