Place the resulting dough in a large rectangular oven tray (the one that comes with the oven), covered with greased baking paper. Bake in moderate oven at 356°F (180 °C) (it bakes quickly).
For the syrup, caramelize 5 tablespoons of sugar, carefully pour on water and boil the syrup for the layers while the caramel dissolves.
Remove the finished cake from the oven, remove the paper. Cut it into strips about 2 wide and add the syrup. Smear it with the cream, prepared by whipping the confectionery cream according to package directions.
Melt the chocolate in a water bath with a little butter and cool it. Mix with the cream.
Cover the first syrupy strip with the chocolaty cream and roll it up like a snail shell. Put it in the middle of a cake plate.
Arrange the other strips, smeared with cream, around it. Set aside a little cream, with which to spread on the entire cake. Decorate with melted chocolate.