There is a sweet story surrounding the origin of this old-fashioned traybake. It was created in the 1800s by a Quaker baker called Henry Chalkley in Tottenham, North London, as a cheap treat for local children. The vivid pink icing was traditionally made using mulberries from trees in the Quaker burial ground. Here we use the rather more easily found (and less creepy) raspberries, plus a splash of food colouring