Remove the panettone top and put it away. Now remove the core, put it in a bowl and stir it with the vanilla ice cream. After that, fulfill the panettone with the mixture and place the lid on the top. Melt the chocolate in a double boiler and add the heavy cream. Cover the panettone with this ganache and sprinkle the chopped nuts over it. Put it in the fridge to get consistency. Tie a Christmas ribbon bow around it.