Place cream in the middle third of the cake, along its full length, and make a large long log as follows. Lift up the two long sides of the cake and bring them over to meet in the middle, sliding one side under the other to encase the cream. Using dressmaking pins to secure the package, join the paper and fold down, holding the paper tightly around the log to help hold its shape. Put the cake in the fridge until ready to serve.