Slice the vanilla pod and scrape out the seeds.
Add to a bowl with the butter, salt and icing sugar and cream together until fluffy
Add the eggs a little at a time mixing them in.
Ad the flour, cornflour and baking powder and mix together to form a dough
Add the cream.
Melt the chocolate in a bowl over boiling water
Divide the cake mixture into two bowls and add the melted chocolate to one bowl.
Preheat the oven to 160C
Grease the cake tin.
Put some vanilla cake mix into the tin, then some chocolate and continue the layers until the mixture has been used.
Swirl with a fork
Bake for 75 - 90 minutes until cooked though.
Leave to cool in the tin for ten minutes before turning it out