Step 1

Preheat oven to 180°C/160°C fan-forced. Grease a 6cm deep, 19cm (base) square cake pan. Line base and sides with baking paper, extending paper 2cm above edges of pan on all sides.

Step 2

Using an electric mixer, beat butter, sugar and vanilla until light and fluffy. Add eggs 1 at a time, beating until combined. Sift over half the flours. Add half the buttermilk. Stir to combine. Repeat with remaining flours and buttermilk. Spoon mixture into pan. Smooth top. Bake for 25 to 30 minutes or until a skewer inserted into the centre comes out clean. Stand in pan for 5 minutes. Transfer to a wire rack to cool. Cover with a clean tea towel. Stand overnight.

Step 3

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

Step 4

Cut cake into 3cm squares. Place coconut in a dish. Using a fork, carefully dip each piece of cake into chocolate mixture. Shake off excess. Toss in coconut. Place on a wire rack set over a baking tray. Stand for 1 hour or until set. Serve.