Divide the mixture into 3 parts. Lay out an 8″ (20 cm) diameter tray with baking paper and bake the 3 layers 1 after the other in a preheated 356°F (180 °C) oven about 20 min. Another option is to divide up the mixture into 3 identical trays and bake all at once.
For the cream mixture, beat the mascarpone with the powdered sugar, then add the cream cheese. Then add the beaten to snow cream. Set aside part of it for smearing and decorating the cake at the end.
To the rest, add 1/2 the biscuits after crumbling them. To assemble the cake, arrange a layer, 1/2 the cream, layer, the other 1/2 of cream and finish with the final layer.
Smear the cake all over with about 2/3 of the set aside cream. Halve some of the remaining biscuits and stick them along the base of the cake, like a border. Put in the fridge for about 2-3 hours.
For the ganache, heat the cream and melt the chocolate in it. Stir until the chocolate is fully melted. Leave to cool.
Take the cake out of the fridge and pour the ganache on top. It will flow elegantly down the sides of the cake. Crumble a few biscuits on top, spray on rosettes and place upright biscuits. It's best to leave the cake overnight for the biscuits to soften.