Heat the oven to 180 degrees C/Gas 4.
1) To make crust, combine biscuit crumbs, sugar and butter. Press down into the bottom of a pie tin to form a crust and bake for about 8 minutes.
2) In the top of a double boiler, melt together candy bars, peanut butter, and single cream, stirring until smooth. Remove from heat and allow to cool slightly. Fold in whipped topping, pour into crust, and freeze for 4 to 6 hours before serving. (For a richer pie, substitute 500ml double, whipped with 100g sugar until stiff peaks form, in place of prepared whipped topping.)
3) When ready to serve, top with additional whipped topping and drizzle with chocolate syrup. Store in refrigerator.