Line an 8" square pan.
Combine the butter, golden syrup and chocolate in a small saucepan. Heat on a very low heat, stirring constantly. Once all melted, add the Rice Krispie cereal. Stir together then press into the pan. Let set 1 hour in the fridge.
Make the Caramel: Combine all caramel ingredients in a medium saucepan and place over medium heat. Let everything melt/combine before cranking up the heat, bringing the mixture to a boil.
Keep stirring everything for at least 5 mins whilst boiling – it will be bubbly and may splash so keep an eye on it and be careful! After about 6/7 minutes, the mixture should be golden/just edging on light brown and thickening up (keep going if not, until you reach this stage). Remove from the heat once it reaches this stage and pour it over the Krispie layer.
Melt each type of chocolate - I use the microwave (blasting for 20 second intervals, stirring in between). Pour them over the caramel and swirl together to cover. Let set at least an hour in the fridge.
Remove and let come to room temp for best slices. Also use a very sharp knife - let it run under hot water for really clean slices!