Beat the mascarpone with the cream, sugar and vanillas in a large bowl. Crumble the cocoa biscuits in a blender or by hand.
Once that's done, start assembling the cake: dip each biscuit well in the compote and make a biscuit layer in the tray. On top, pour 1/3 of the mascarpone/cream mixture.
On it, sprinkle 1/3 of the crumbled cocoa biscuits. Then repeat this order of products. Once you've assembled the cake, grate 1/2 the milk chocolate over it.
Cut up a banana and distribute it on top for decoration. Grate the rest of the chocolate.
It needs to sit for about 24 hours in the fridge before serving.