Method

​1 Lightly grease a 9 x 13 inch (23 x 13 cm) cake tin with butter.

2 In a large saucepan slowly melt together the butter, golden syrup, the large marshmallows and the chocolate over a very low heat. A low heat will ensure the chocolate won't burn. This will soon become very smooth and silky.

3 Stir in the puffed rice and raisins and mix before adding the mini marshmallows.

4 Spoon into the greased cake tin and smooth out, ensuring the mixture goes right into the corners. Place in the fridge to cool for approximately 30 minutes.

5 Once the crispy cake has cooled remove from the fridge. Place a heatproof bowl over a saucepan of boiling water, making sure it doesn’t touch the water. Melt the white chocolate in the bowl and once nice and smooth, drizzle over the crispy cake.

6 Melt the milk chocolate in the same way but only drizzle over half of the melted chocolate. The rest will be saved for a final drizzle.

7 Scatter the chocolate raisins, mini marshmallows and white chocolate chunks over the crispy cake before drizzling with the remaining milk chocolate. Allow to cool thoroughly before removing from the tin and cutting.