For all you walnut whips fans! A chocolate chip and walnut sponge. Filled with a deliciously gooey marshmallow butter icing. I topped the cake with dark chocolate ganache and then halved some walnut whips as decoration, along with some crushed walnuts. All a very tasty combination if I say so myself!! I made this for my mum's birthday as walnut whip is one of her favourite chocolate treats.