Line a 900g loaf tin with a double layer of cling film. Melt the butter, chocolate and sugar in the microwave on medium for 2-3 mins or in a bowl set over a pan of simmering water over a low heat. Stir in the cinnamon, macaroons or the coconut biscuits and nuts.
Pour the mixture into the prepared tin, smooth over the surface with a knife and cover completely with cling film. Leave in the fridge to set for at least 2 hrs. To serve, set on a plate, remove cling film and sprinkle with desiccated coconut. The cake is fairly rich, so slice into thin pieces and serve with fresh fruit or ice cream if you like.