Instructions

Line a 19cm x 29cm (base measurement) slice pan with baking paper, allowing the 2 long sides to overhang. Reserve a quarter of the chopped biscuits for garnish. Place remaining biscuits in a large bowl.
Heat the chocolate, butter and sugar in a saucepan over a low heat, stirring for 5 minutes or until the mixture is well combined and smooth. Remove from the heat. Whisk in the egg until well combined. Cool for 10 minutes.
Pour the chocolate mixture over the biscuits and stir until well combined. Spoon into the prepared pan. Use the back of a spoon to press firmly into the pan. Place in the fridge for 2 hours or until firm.
To make the icing, stir the chocolate and butter in a small saucepan over low heat until melted. Cool for 10 minutes. Spread over the slice. Sprinkle with the reserved chopped biscuit. Place in the fridge for 1 hour to set. Cut slice into squares or rectangles.