Preheat oven to 350ºF (180ºC).
Chocolate Crust: In a bowl, combine cookie crumbs, butter and cinnamon. Press into bottom and sides of a 9 inch (23 cm) pie plate. Bake for about 10 minutes or until firm. Let cool completely.
In a large saucepan, melt butter over medium heat. Stir in marshmallows and coffee; stirring until melted and smooth. Stir in rum. Remove from heat and let cool slightly.
Meanwhile, in a large bowl, whip cream and vanilla to stiff peaks. Fold in some of the whipped cream into the marshmallow mixture to lighten and then fold in remaining cream and toffee bits. Spread mixture into prepared crust and refrigerate about 4 hours or until firm and chilled.
Before cutting, sprinkle top with chocolate to serve.