Break the biscuits into small pieces directly into a large bowl. Add the pecans, pistachio nuts and cherries, and mix together.

Put the rest of the ingredients into a separate bowl and place over a pan of simmering water until the butter and chocolate have melted.

Combine the biscuit mix with the chocolate mixture. Line an 8 x 12 inch plastic container with plastic wrap, leaving plenty of extra plastic wrap at the edges to help turn the cake out later. Pour in the mixture, pressing down hard to pack nicely, then fold the plastic wrap over the top. Leave in the fridge for a few hours to firm up, then turn out and cut into chunky slices.