If you want the marshmallows to hold their shape, then put them in the freezer a couple of hours before starting your recipe (I also like to ensure they are separated from one another).
Melt in a pan on a low heat butter (100g), milk chocolate (175g), dark chocolate (85g) and golden syrup (3 tbsp).
Once melted set aside 100ml of the melted chocolate mixture to be used later, leave the rest in the pan but turn off the heat.
Crush the biscuits (150g) into small pieces (take a look at the video for an idea of the size you want) and fold into the chocolate mixture in the pan.
Chop the cherries (40g) into halves or thirds depending on their size and add to the pan. Also mix in raisins (50g) and mini marshmallows (50g).
Lay out the baking parchment onto a tray (approx 20cmx26cm) and spoon the mixture onto it. Press down firmly on the mixture to compress it and form an even layer.
Pour the 100ml of melted chocolate which you set aside earlier evenly across the top of the mixture. The idea is to fill in any gaps with it, and create a slightly smoother top surface. The liquid should only just cover all of the surface, so you may need to spread it with a spoon to distribute it evenly.
Finally put it in the fridge to set. It will be set enough to eat in about two hours, but I prefer to leave it overnight to give it a enough time to fully harden.