1.Preheat oven to 180°C (160°C fan-forced). Grease oven trays; line with baking paper.
2.In a small bowl, beat butter and sugar with electric mixer until light and fluffy. Stir in sifted flour and cocoa, then cornflakes and coconut in 2 batches.
3.Place 3-level-teaspoon portions of mixture about 3cm apart on oven trays.
4.Bake about 12 minutes or until biscuits are firm and browned lightly. Stand biscuits 5 minutes before lifting onto a wire rack to cool.
5.Make chocolate icing. Spread warm chocolate icing quickly over biscuits.
6.In small heatproof bowl, combine sifted icing sugar and cocoa. Stir in butter and enough water to make a stiff paste. Stir over small saucepan of simmering water until spreadable.
Store in an airtight container for up to a week.Note