Line a 20 cm square baking tin with baking paper.

Melt the golden syrup and butter in a saucepan over a medium heat.

When it starts to bubble, take it off the heat and immediately add the dark and the milk chocolate. Stir until all the chocolate has melted.

Add the chunks of digestive biscuit and raisins and mix well.

Add to the lined tin and pat down firmly, pressing all the way to the edges.

Now melt the milk chocolate for the topping in a heat proof bowl over a pan of simmering water.

Pour over the top of the tiffin and spread all over.

You can decorate it with other novelty chocolates if you like, maltesers work well.

Leave to chill in the fridge for 2-3 hours. Once set, carefully remove from the tin and cut into pieces.