1.Lightly grease and line a 20cm x 30cm slice pan with baking paper, extending paper 5cm over long sides.
2.In a large bowl, combine rice bubbles, icing sugar, coconut, peanuts and cocoa. Mix well.
3.In a medium saucepan, melt copha on low. Cool 10 minutes. Stir in peanut butter.
4.Make a well in dry ingredients. Pour in copha mixture and mix very well. Press firmly over base of pan. Chill until firm.
5.Meanwhile to make topping; in a heatproof bowl, combine chocolate and butter. Place over a saucepan of gently simmering water. Stir until melted. Pour over slice, spreading evenly. Sprinkle with extra chopped peanuts if liked. Chill until set.
6.Cut into small squares or rectangles to serve.