Step 1: Prepare the Pan
Preheat your oven to 350°F (175°C). Grease an 8×8-inch square baking pan and line it with parchment paper, leaving some overhang on the sides for easy removal. Set aside.

Step 2: Whip the Eggs and Sugar
In a large mixing bowl, combine the eggs and caster sugar. Using an electric mixer on high speed, beat for 8-10 minutes until the mixture is thick, pale, and tripled in volume. When you lift the beaters, the mixture should fall in thick ribbons that hold their shape for a few seconds. This step is crucial for a light, fluffy sponge.

Step 3: Prepare the Dry Ingredients
While the eggs are whipping, sift together the flour, baking powder, and salt in a separate bowl. Set aside.

Step 4: Combine Butter and Vanilla
In a small bowl, mix the melted (but cooled) butter with vanilla extract and hot water. This helps the butter incorporate more easily without deflating the eggs.

Step 5: Fold in Flour
Gently sift half the flour mixture over the whipped eggs. Using a large spatula, fold carefully from the bottom of the bowl up and over, turning the bowl as you go. Repeat with the remaining flour. Work gently to preserve all those air bubbles—they’re what makes your sponge light.

Step 6: Add Butter Mixture
Pour the butter mixture around the edge of the bowl, then fold it through the batter with the same gentle folding motion. Stop as soon as everything is combined—overmixing will deflate the batter.

Step 7: Bake the Sponge
Pour the batter into your prepared pan and gently smooth the top. Bake for 23-25 minutes, or until the cake is golden, springs back when lightly touched, and a toothpick inserted in the center comes out clean. Don’t overbake or the sponge will be dry.

Step 8: Cool Completely
Let the cake cool in the pan for 10 minutes, then use the parchment overhang to lift it onto a wire rack. Cool completely—at least 2 hours, or ideally overnight. Day-old sponge is actually easier to work with because it’s slightly firmer and less crumbly.

Step 9: Cut into Squares
Once completely cool, use a sharp serrated knife to trim the edges (baker’s treat!), then cut the cake into 16-20 even squares, depending on your preferred size. Traditional lamingtons are about 2 inches square.

Step 10: Prepare the Chocolate Icing
In a medium bowl, sift together the powdered sugar and cocoa powder. Add the melted butter, milk, and vanilla. Whisk until completely smooth. The icing should be thin enough to coat the cake but thick enough to cling—about the consistency of heavy cream. Add more milk by the tablespoon if needed.

Step 11: Set Up Your Coating Station
Pour the chocolate icing into a shallow bowl. Place the desiccated coconut in another shallow bowl or on a large plate. Line a baking sheet with parchment paper for the finished lamingtons.

Step 12: Dip and Coat
Working with one square at a time, use two forks to dip the cake into the chocolate icing, ensuring all sides are coated. Let excess icing drip off briefly, then immediately roll the square in the coconut, using your hands or forks to coat completely. Place on the prepared baking sheet. Repeat with remaining squares.

Step 13: Set the Coating
Let the lamingtons sit at room temperature for 30 minutes to 1 hour until the icing sets. They’re now ready to serve!