For the chocolate bananas, peel the banana, cut into pieces and mash with vanilla sugar and lemon juice. Finely grate the biscuits and knead with the banana puree to a firm mass.
Pour into a pastry bag with a large, smooth nozzle and pipe about 4-5 cm strips (about 20 pieces) onto baking paper. Leave to dry open overnight at room temperature.
Heat the chocolate icing in a water bath or in the microwave. Using a fork, dip the banana sticks individually into the glaze and leave to dry on a sheet of baking paper.