Beat the tiramisù for 3 minutes and divide into 3 containers.
Melt the chocolates separately and mix each one with a third of the beaten tiramisù.
Assemble the dessert by alternating a layer of Genoise with a layer of tiramisù of each flavour: first white chocolate, then milk chocolate and finally dark chocolate.
Leave in the refrigerator for 2 hours.
Remove from the mould.