Cortices are spread and each smear with melted butter. Is put on top of each other, cut into four so as to obtain uniform rectangles. Each banana is cut across the two. Placed in one of the resulting rectangles, sprinkle with grated chocolate and walnuts, put a little butter and rolled roll. Rolls put in greased pan and bake at 180 C until golden. Yolks for Sabayon sauce mixed with brown sugar and beat with wire. Cream boil, add the broken chocolate and allow to melt. The mixture was poured into yolks and stir. Everything is transferred into a small saucepan and boil briefly on low heat, stirring with a wire. Finally flavored with rum essence. Serve as a plate pour the sauce and place banana roll. Decorate with chocolate drops by itself sauce.