Let the ice cream soften either in the fridge for a while, or out in the kitchen. Line a 20cm / 8 inch springform tin with clingfilm, both in the bottom and sides of the tin so that you have some overhang at the top. Empty the slightly softened ice cream into a bowl and mix in the peanuts, 150g / 1 cup chocolate and peanut butter morsels or chocolate chips, Crunchie bar shards and 100g / 1 cup of the Bourbon biscuits crumbs. Scrape the ice cream mixture into the springform tin, flattening the top like a cake, cover the top with clingfilm and place in the freezer to firm up. Serve the cake straight from the freezer, unmoulding from the tin and pulling the clingfilm gently away, before putting on a plate or cake stand. Let it stand and soften for about 5 minutes before cutting. Sprinkle the top of the cake with the extra 50g / ¼ cup of chocolate and peanut butter morsels or chocolate chips, and the remaining Bourbon biscuits crumbs. Cut into slices and serve with the butterscotch and chocolate sauces, letting both dribble lacily over each slice. If two sauces sound like too much trouble - they're not - just opt for the chocolate peanut butter sauce. It's hard to find an argument against it.
Comments, questions and tips