Break the biscuits into small pieces directly into a large bowl. Add the pecans, pistachio nuts, cherries and bits of meringue. Put the rest of the ingredients, except the cocoa powder, into a bowl and put over a pan of simmering water on low heat to melt.
Mix the ingredients together and place in the container which acts as your mold. To help with turning out, line a 12 by 8-inch (30 by 20 centimeter) container with cling film, first leaving plenty of extra film at the edges to fold over the top.
Leave in the refrigerator to firm up then turn out and cut into chunky slices. This cake can be kept in an airtight container and actually improves after a couple of days.