Step 1: Prepare the Tin

• Line a 20cm (8-inch) square tin with parchment paper, making sure it extends over the edges for easy removal later.

Step 2: Crush the Biscuits

• Place the digestive biscuits in a large mixing bowl and crush them with a rolling pin or the back of a spoon. You want a mix of fine crumbs and small chunks for texture.

Step 3: Melt the Butter and Golden Syrup

• In a saucepan, melt the butter and golden syrup together over low heat, stirring occasionally. Once melted, remove from the heat and stir in the cocoa powder until smooth.

Step 4: Combine the Ingredients

• Pour the melted butter, syrup, and cocoa mixture over the crushed biscuits. Add the raisins and mix well until all the ingredients are evenly coated.

Step 5: Press the Mixture into the Tin

• Spoon the mixture into the lined tin and press it down firmly with the back of a spoon or spatula, ensuring it’s evenly distributed and compact.

Step 6: Melt the Chocolate

• Melt the milk chocolate in a heatproof bowl over a pan of simmering water (or in the microwave in short bursts). Once fully melted, pour the chocolate over the biscuit mixture and spread it evenly with a spatula.

Step 7: Chill the Tiffin

• Place the tiffin in the fridge for at least 2 hours, or until fully set.

Step 8: Slice and Serve

• Once the tiffin has set, remove it from the tin using the parchment paper overhang. Slice into squares or bars and enjoy!