line a 30cm x 20cm dish with cling film.

Place the butter, golden syrup and both chocolates into a glass bowl and heat in the microwave until melted. Heat for 30 seconds at a time stirring each time to avoid the chocolate burning.

In another bowl add the rice crispies and raisins. Pour over the chocolate mixture and fold together until well combined.

Scrape the mixture into the cling filmed dish and press down flat into the corners. Put in the fridge to set.

Once set slice into 20 bars, store in a airtight container.