None of the parts of this stunning cake are difficult; most can be made ahead. The marzipan can be made a week ahead of time. The cake can be made a day ahead and wrapped, or frozen for up to 1 week. The pudding filling can be made the day ahead - fold in the whipped cream just before assembling the cake. Allow about 1 hour to assemble and decorate the cake.
A heavy-duty stand mixer is a must for mixing the marzipan mixture.