PRE-HEAT THE OVEN TO 170ËC/150ËC FAN/GAS 3 PREP - Butter the loaf tin or line with baking parchment. Peel the bananas and chop into small pieces. BEAT - Beat the butter, muscovado sugar and caster sugar together until light and creamy. ADD - Add the eggs, one at the time, beating well after each addition. Sieve the flour and fold it into the mixture with a metal spoon. Fold in the baking powder, ground hazelnuts and vanilla extract. FOLD - Gently fold the banana and chocolate chips into the cake mixture. Make sure you do not over-mix. BAKE - Pour the cake mixture into the loaf tin. Sprinkle the top with the demerara sugar. Bake for 1 hour.