SERVES: 8-10 (depending how big the slices are)
TIME: 1 hour
For the cake:
170g butter
170g maple sugar (golden caster sugar if you can't get maple sugar)
225g self-raising flour, sifted
2 large eggs / 3 medium eggs
3½ tbsp vanilla yoghurt
3 large ripe bananas, mashed with a fork
For the icing and decoration:
250g butter, very soft (room temperature)
500g icing sugar
2 tsp vanilla extract
3 ripe bananas
60g blanched hazelnuts
Pre-heat the oven to 180C and have ready an 8" cake tin (or you could use 2 x slim 8" sandwich tins). Then lightly grease and line the base of the tin with greaseproof paper.
In a large bowl, cream the butter and sugar with an electric whisk if you have one, together until it's soft and fluffy. In a separate bowl whisk the eggs with a fork and then add slowly to the creamed mixture a little bit at a time.
Mash the bananas in a separate bowl if you haven't already done so. The bananas do need to be ripe otherwise they won't mash properly. With a large metal spoon, add the bananas and yoghurt to the mixture and stir in well. Don't worry if the mixture starts to look like it's curdled - it's just the bananas and yoghurt mixing in.
Finally, add the sifted flour and mix in well. Pour the cake mixture into your tin and bake for 40-45 minutes or until the skewer comes out clean.
Turn the cake out onto a wire rack and leave to cool.
To make the icing, cream the butter alone with an electric whisk until it's really light and fluffy. Add the icing sugar a bit at a time - the icing sugar will cloud up but you can use a tea towel to partially cover the bowl which will help to reduce the dust cloud.
Once all the icing sugar is incorporated, add the vanilla extract and whisk together really well.
Put the icing to one side to prepare your hazelnut topping. In a dry frying pan over a medium heat, gently toast the hazelnuts until brown - be really careful they don't catch and burn. This should take about 4-5 minutes. Then in either a food processor or a plastic bag with a rolling pin, crush the hazelnuts until broken down - not too much otherwise it will turn to dust.
Once the cake has cooled, slice it in half - I find a serrated bread knife works best. Use half the icing on the middle of the cake. Then slice up the bananas into strips and arrange on top of the icing. Then arrange the top half of the cake and spread over the remaining icing. Finally, use a fork to fluff up the icing a little for texture and sprinkle the toasted hazelnuts over the top