Butter the pudding bowl or bowls and pop a disc of parchment paper at the bottom of each to prevent sticking.
Place a metal bowl over a pot of simmering water. Pop the butter and golden syrup into it and melt. Once melted turn off the heat and add the chocolate pieces and allow to melt before adding the remaining ingredients except the white chocolate.
Spoon the mixture into the prepared pudding bowls and press down with a spatula to remove and bubbles. Set in the fridge for 2 hours.