For the sponge cake

Ideally, make the cake the night before or see my Kitchen Notes below if you want to make everything on the same day

1. Make sure that the butter, eggs and milk are at room temperature. If they are not at room temperature, this can cause the batter to curdle, which will result in a dense cake.
2. Preheat the oven to 180°C (350°F) (without fan).
3. Butter a baking pan measuring approximately 17 x 27 x 4 cm/7 x 11 x 1.5 inch, and line the bottom with greaseproof paper.

If using a food processor:

1. Place all of the ingredients for the cake into a large food processor and blitz until everything is thoroughly combined.
2. If the batter looks a bit curdled (which can happen if not all of the ingredients are at room temperature), blitz for a few more seconds.

If using a stand mixer or by hand:

1. Cream the butter and sugar until it is pale and fluffy. This step takes about 2-3 minutes on low speed.
2. Add the flour, baking powder and cornflour.
3. Mix until everything is just combined.
4. In a jug, whisk together the milk, eggs and vanilla.
5. Slowly add the liquid ingredients to the batter.
6. Mix until everything is well combined, but take care not to over-mix.

To bake the cake

1. The batter should be pale yellow and quite thick.
2. Pour the mixture into the prepared baking pan and bake for about 30-35 minutes, or until a skewer inserted into the centre of the cake comes out clean. Check on the cake after about 20 minutes, as you may need to cover the cake with some foil if it is browning too quickly.
3. Leave the cake in the pan for about 5 minutes before turning it out onto a wire rack to cool, with the bottom of the cake facing up. This will help to ensure that the top of the cake flattens while it cools. Remove the baking paper.

To make the chocolate icing

1. Melt the butter and chocolate over low heat in a bain-marie (or a large bowl over a pan of simmering water).
2. Add the icing sugar (powdered sugar) and whisk in the milk until you have a thick, but slightly runny, mixture. The icing needs to be thick enough to coat the cakes, but runny enough to only leave a light coating.
3. Leave the bain-marie on the stove over very low heat.

To assemble the lamingtons

1. Using a serrated knife (ideally a long, serrated bread knife), remove the edges of the sponge by cutting a thin slice. This is a cook's treat!
2. Cut the sponge into 32 squares, or whatever size you wish. Keep in mind that, once coated in chocolate and coconut, the cakes will be much bigger in size.
3. Pour the dessicated coconut onto a large plate.
4. Using two forks, dip a piece of sponge into the chocolate icing mixture, making sure that all sides are lightly coated, and allow any excess icing to drain off.
5. Then roll the chocolate-coated sponge in the dessicated coconut, and place the lamington on a wire rack to dry.
6. Repeat with the remaining sponge pieces.
7. If the icing mixture becomes too thick, whisk in some milk to thin it out.
8. Let the lamingtons set on a wire rack for about 30-60 minutes.