Line a 20cm baking tin with baking paper.
Chop the milk and dark chocolate into small chunks, and break up the digestive biscuits into pieces.
Place the golden syrup and the butter into a saucepan, cook over a medium heat until the butter is completely melted. Don't boil it.
Add in the chopped milk and dark chocolate and mix it well until the chocolate has all melted and the mixture is well combined.
Take it off the heat, then add in the Maltesers, digestive biscuits, and raisins, mix it until it’s well combined.
Place the mix into the baking tin and press down into the edges.
Set it aside whilst you prepare the topping. Melt the milk chocolate in a heat proof bowl over a pan of simmering water.
Once melted, pour it over the tiffin and spread it into the edges.
Scatter over some more Maltesers, some whole and some crushed, then place it into the fridge for a few hours until it has set.
Cut it into portions and enjoy. It will keep for up to a week in an airtight container.