Preheat oven to moderate 180°C/350°F/gas mark 4.

Prepare a 4 ½ cm (1¾ inch) deep, 23cm x 33cm (9”x 13”) baking pan by lining with non-stick paper.

In a stand mixer bowl place eggs, sugar and salt. Using the whisk attachment, beat on high for 15 minutes.

While the eggs and sugar are beating sift the cornflour and baking powder at least 3 times.

After 15 minutes add vanilla and beat on high for another 5 minutes. The mixture should have at least tripled in size, be light in colour and very foamy.

Sift flour mixture over the egg mixture. I like to use a whisk but you can also use a large metal spoon to lightly fold the flour in. Some people like to use a wooden spoon but I find it too heavy. Heavy handling now will result in a flat tough sponge. If you are using butter, thoroughly fold it in now but lightly.

Spread mixture into your prepared pan and smooth out evenly. Some cooks at this stage drop the pan onto the bench top to even out the air bubbles! I have never had that much courage!

Bake in preheated moderate oven for 22-25 minutes. The sponge will rise quite a lot but then settle back down. Don’t be tempted to open the oven to peak. I also warn the family to walk gently past the oven! When baked the sponge will have shrunk very slightly from the sides and should feel springy when pressed gently.

Sift the icing sugar and cocoa into a heatproof bowl.

Stir in the butter and ½ cup milk. Set the bowl over a pan of hot water. Stir until icing is smooth adding more milk to thin the icing if needed. I find I need more than ½ cup but not quite ¾ cup of milk

Cut the sponge cake into 24 rectangular pieces – 6 across and 4 down. To be particular you can trim the crusts.

Keep the icing over the hot water to keep it melted. Place desiccated coconut in a shallow bowl.

Dip each piece into the chocolate icing, allow excess to drip off

Toss gently into the coconut.

Stand cakes on a wire rack to set, about 2 hours.