Step 1

Preheat oven to 180°C/160°C fan-forced. Grease a 20cm x 30cm lamington pan. Line with baking paper extending paper 2cm from edge of pan at long ends.

Step 2

Place butter, brown sugar, egg and vanilla in a large bowl. Stir until well combined. Sift over flours and cocoa powder. Add 1/2 cup coconut. Stir to combine. Spread mixture into prepared pan. Bake for 25 to 30 minutes or until firm to touch.

Step 3

Make Chocolate icing: Sift icing sugar and cocoa powder into a medium heatproof bowl. Add butter and boiling water. Stir until smooth.

Step 4

Spread hot slice with icing. Sprinkle with remaining coconut. Set aside to cool completely in pan. Cut into pieces. Serve.