Tiffin: 1. In a saucepan, melt the butter, sugar, syrup and cocoa. . Meanwhile, crush the biscuits with a rolling pin in a baking bowl. When the saucepan mixture has melted, add to the biscuits and raisins. Stir to combine. 2. Pour mixture over the cooled caramel and flapjack and press down to set. 3. Melt the chocolate in a bowl over a pan of simmering water and pour over the tiffin, caramel and flapjack already in the tin. 4.Pop the tin into the fridge and leave for about 1 hour to set. To serve, cut into 16-20 pieces.