Preheat your oven to 180C / 350F / 160C fan forced and line a lamington tin (approx 22cm x 33cm) with baking paper.
Sift together the flour, baking powder and salt and mix well.
Beat together the butter and sugar until very light and fluffy. Add the eggs one at a time, beating well between each. Scrape down the sides of the bowl from time to time.
Add the vanilla and mix through.
Add 1/2 the flour mix and fold through gently with a spatula. Now add the milk, fold through. Add the remaining flour and fold through gently again until just combined.
Spread the batter evenly in prepared tin. Bake for 25-27 minutes, turning at the halfway mark, until the top is golden and a toothpick inserted comes out clean. Allow it to cool slightly, then turn out onto a wire rack to cool completely.
Once cooled, cut the edges off the cake then cut it into squares.
Place in the fridge for at least 2 hours or the freezer for half an hour to get firm.
FOR THE GLAZE
Combine the icing sugar, cocoa and boiling water in a deep bowl and mix well to a syrup consistency.
Place 1/3 of the coconut into a separate bowl. Set two wire racks over baking paper lined trays.
Using two forks, dip a square of sponge into the chocolate glaze turning to coat well. Let it drain a little then transfer to one of the wire racks. Repeat with 2 more squares.
Take the first square and use clean forks to roll it in coconut then transfer to the second tray to set. Repeat 2 more times.
Now repeat the process with the whole batch, replenishing the coconut as required.
Equipment: lamington tin or a 9x13 tin with high sides, or 2 square baking tins.
For best results you should always weigh ingredients like flour and sugar. Kitchen scaleslike these are relatively cheap but if you can’t weigh the ingredients, use the spoon and level method (don’t scoop).
This recipe can be halved and made in an 8x8 inch square baking tin or, if you don't have a lamington tin make the full recipe in two square tins.