Chop up the dark chocolate and place in a heat proof bowl, with the clotted cream and the syrup. Place over a saucepan full of boiling water and stir until melted together.
Once the mix has completely melted, take off the heat and allow to cool slightly.
Alternatively place the chopped chocolate, golden syrup and clotted cream in a microwave proof bowl and microwave in 30 second intervals until melted, stirring each time.
Put aside 4-5 tablespoons of the melted chocolate.
Fold in the biscuits, marshmallows and the cherries into the rest of the melted chocolate until well combined.
Pour into a square baking dish lined with greaseproof paper, pressing the mixture into the corners with a spatula or back of a spoon.
Give the mix one last press over the top and place in the fridge for 10 minutes to harden.
Take out of the fridge and use the remaining chocolate to drizzle over the top, then add the smarties and any additional decorations you want. (We used chocolate stars!)
Return to the fridge to set for 4 hours or ideally overnight.
Once set, cut into 10 equal squares and enjoy!