Preheat your oven to 350°F (180°C) and grease and line an 8-inch square baking pan with parchment paper, leaving some overhang for easy removal.

In a large bowl, beat the softened butter and granulated sugar together with an electric mixer for 3 to 4 minutes until the mixture is pale and fluffy.

Add the eggs one at a time, beating well after each addition, then stir in the vanilla extract until fully incorporated.

Gently fold in the self-rising flour alternately with the milk in two batches, stirring until a smooth batter forms without overmixing.

Spread the batter evenly into the prepared baking pan and bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out clean.

Allow the sponge cake to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing it horizontally in half.

Spread the raspberry jam evenly over the bottom cake layer, carefully place the top cake layer back on, and slice the sandwich into 12 equal squares.

To make the chocolate icing, sift the powdered sugar and cocoa powder into a heatproof bowl, then whisk in the boiling water and melted butter until smooth.

Place the desiccated coconut in a shallow bowl or pie dish next to your icing station.

Using two forks, dip each cake square into the warm chocolate icing until fully coated, letting any excess icing drip back into the bowl.

Immediately roll the chocolate-coated square in the desiccated coconut until all sides are evenly covered, then transfer to a wire rack to set.

Let the lamingtons sit for 15 minutes to allow the chocolate coating to firm up, then serve them alongside a hot cup of tea or coffee.