Put biscuits in plastic bag and bash with rolling pin to get big and little sizes crumbs
Put brazil nuts into plastic bag and bash to get different sized nut rubble
Chop chocolate and put into pan with butter and syrup
Melt, stirring all the time, over a low heat
Take off the heat
Stir in biscuits and nuts
Add cherries and marshmallows
Stir really well to coat everything in chocolate
Tip into tin/tray and chill for about 6 hours then cut into pieces and store in airtight tin