Grease and line with baking paper a 20x30cm lamington pan.
Place butter, sugar, egg and vanilla in a bowl, stir until combined.
Sift flour and cocoa into bowl, add ½ cup coconut.
Stir until mixture has combined.
Spread mixture evenly into pan.
Bake for 25-30 minutes or until just firm.
ICING
Sift icing sugar and cocoa into bowl.
Add butter and boiling water, stir together.
Spread warm slice with icing.
Sprinkle remaining coconut over slice.
Recipe Notes
TIPS FOR FREEZING SLICES
you can freeze the slices as a whole or cut into individual pieces;
wrap the slice in plastic wrap then wrap in a layer of foil and place into an airtight container in the freezer (these 3 steps will keep your slices tasting great!);
slices with a soft filling (or cheesecakes) don’t tend to freeze well;
slices kept in the freezer will taste best within the first month, but can last longer.