Need something a little bit naughty to go with your picnic? This chocolatey treat will do the trick, and because it's so rich a little goes a long way.
Place the butter, dark chocolate and syrup into a heatproof bowl and warm over a pan of simmering water, ensuring the bowl doesn’t touch the water, for 5-10 minutes or until melted. Stir then set aside to cool.
Roughly break the biscuits. Fold into the dark chocolate mixture with 50g (2oz) of the white chocolate and all the fruit and nut mix. Spoon into a 20cm (8in) square tin, smooth the surface, then scatter over the marshmallows.
Cover and place in the fridge for 3 hours or until set. Using a sharp knife cut into 9 squares. Then halve each square to make triangles. Keep cool.
They can be stored in an airtight container in a cool dark place for 2-3 days – after this time they will not be as fresh.
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