Add the Bourneville, butter, and syrup into a heatproof bowl over some simmering water and let the ingredients melt whilst frequently stirring them.
When melted, let the chocolate mixture cool for a few mins before adding in the chocolate fingers, Haribo, Mini chocolate eggs and marshmallows and mixing until everything is well coated with the chocolate mixture.
Pour into a lined baking tray and spread the mixture out to the corners.
Refrigerate the rocky road cake for 2 hrs minimum or overnight and then cut into squares before serving.