Heat the oven to 180 C / 355 F. Grease a 23 cm / 9-inch square baking pan and line it with parchment paper.

In a mixing bowl, whisk the eggs and sugar together for 2 to 3 minutes until pale and slightly foamy.

Whisk in the oil, milk, vanilla, and rum until smooth.

In a separate bowl, stir together the flour, baking powder, and salt. Fold into the wet ingredients until just combined. The batter will be thin.

Pour the batter into the pan and smooth the top. Bake for 25 minutes, until a toothpick comes out clean and the top springs back when pressed.

Cool the cake in the pan for 10 minutes, then turn it out onto a wire rack and cool completely, about 1 hour, before cutting.

Trim the edges of the cooled cake, then cut into cubes about 4 cm / 1.5 inches. You'll get about 20 to 24 cubes.

Combine the sugar, cocoa powder, milk, and butter in an 18 cm / 7-inch saucepan. Warm over medium-low heat, whisking often, for 4 to 5 minutes until smooth and thick enough to coat the back of a spoon. Keep it warm over low heat while you work.

Spread the shredded coconut in a shallow bowl or plate.

Working in batches of 5 to 6 cubes, dip each cube in the warm glaze with a fork, let the excess drip off, then roll immediately in the coconut until fully coated.

Set the finished cubes on a wire rack or plate to set, about 20 minutes, before serving.