Preheat oven to 180°C. Spray a 20 x 30 cm sponge roll tin with non stick baking spray.
Mix all the chocolate rough ingredients in a large bowl. Press into the prepared tin and bake for 20 minutes. Cool in the tin while you make the Icing.
Measure Chelsea Rich Chocolate Icing Sugar into a bowl, add in butter and hot water, mix well until smooth. Spread over the chocolate rough while still warm in the tin. Icing should spread easily; if too thick add a little more hot water to allow it to spread well.
Sprinkle the coconut over and cut into squares, leave to completely set and go cold in the tin before removing. Store in an airtight container.