1. Butter the bread slices and arrange on a clean work surface, buttered side up.
2. Slice the bananas.
3. Reserving 4 slices for decoration, divide the remaining on 2 slices in a single layer.
4. Generously sprinkle grated chocolate over the banana.
5. Cover with other 2 slices of bread and lightly pressing down to pack sandwich firmly.
6. Trim the crusts and quarter into triangles or squares.
7. Arrange quarters neatly on individual plates.
8. Decorate each quarter with slice of banana.
9. Serve as a tea time snack at a party.