1. To make the cake batter, cream together the butter and sugar into a smooth paste. Crack the three eggs into the same bowl and whisk it all together with an electric hand whisk until light, airy and smooth. Next, add the self-raising flour, baking powder and all the spices. Fold the flour into the batter until nice and smooth.
2. Take 2 of the bananas and mash them in a small bowl with a fork until they make a lumpy paste. Add this to the cake batter, along with the raw rhubarb chopped into small chunks and stir until everything is combined evenl
3. Line a loaf tin with baking paper and pour the mixture in. Halve the 3rd banana width ways, lay across the top of the batter in the tin and top with a handful of pumpkin seeds. Bake at 170 degrees celsius for 45 minutes until a knife comes out clea

Tip: If it starts to brown too quickly on top after half an hour then cover with tin foil