Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Separate the eggs for the sponge cake. Beat the egg whites, 4 tablespoons of cold water and 1 pinch of salt until stiff with the whisks of the mixer, adding 100 g of sugar at the end.
Stir in the egg yolks one after the other. Mix flour, starch, cinnamon and baking powder, sieve onto the egg mixture and fold in. Spread on a baking tray lined with baking paper. Bake in a hot oven for 8-10 minutes.
Take the sponge out of the oven. Turn onto a tea towel sprinkled with sugar immediately. Carefully remove the paper. Roll up the short side of the sponge cake using the tea towel and let it cool down.
For the cream, soak gelatine in cold water. Bring the milk to the boil, except for 5 tablespoons. Stir pudding powder, 25 g sugar and the rest of the milk until smooth. Stir into the hot milk, bring to the boil and simmer for about 1 minute while stirring.
Take it off the stove. Squeeze the gelatine. Dissolve in hot pudding while stirring. Put it in a cold place, stirring frequently.
Chop the chocolate, stir into the pudding. Whip cream until stiff and fold in. Peel and halve bananas and sprinkle with lemon juice. Unroll the sponge cake, spread the pudding cream on top. Place the bananas on the edge along a short side.
Roll up the sponge cake from the banana side using the tea towel. Chill for at least 2 hours. Dust with icing sugar and decorate with caramel spread. Cut diagonally into pieces.