Ultimate chocolate fridge cake

Line the base and sides of a 20cm square tin with baking parchment. Tip the milk chocolate (125 g) and dark chocolate (100 g) into a large heatproof bowl. Add the butter (125 g) and golden syrup (125 g) and set the bowl over a pan of barely simmering water to melt. Stir until smooth, remove from the heat and leave to cool slightly.

Combine the biscuit pieces (1 pack), pretzels (1 pack), nuts and raisins (1 pack) in a bowl. Pour in the melted chocolate and mix to combine. Spoon into the tin and spread level. Cover the surface with a sheet of baking parchment and press flat using a flatbottomed ramekin or glass. Leave at room temperature for about 2 hours to cool and firm, then chill for 20 minutes.

For the topping, melt the milk chocolate (75 g), dark chocolate (50 g) and white chocolate (75 g) in separate bowls. Stir until smooth and leave to cool slightly. Using a teaspoon, drop random dollops of milk chocolate over the top of the chilled cake, then do the same with the dark and white chocolate, filling in the gaps. Gently shake the tin to level the chocolate, then marble the chocolates together using a wooden skewer.

Chill for about 30 minutes, or until the chocolate has set. Using the lining paper, lift the fridge cake out of the tin and cut into squares or fingers to serve.