Girl Guides Mars bar cake. I've searched for this recipe for years. 3 Mars bars (about 60g each) 75g butter 2 tablespoons golden syrup 100g puffed rice cereal, e.g. Rice Krispies 300g milk chocolate Chop the Mars bars and melt in a pan with the butter and syrup, keep stirring until blended together, pour over cereal and mix until coated. Press into a lined tin and put into the fridge to set. Melt chocolate and pour over. Fridge again, cut and serve.