Preheat your oven to 180C.

Crack in an egg one at a time.

Then, drizzle in vanilla extract.

Gently stir in plain flour and baking powder.

You would want to mix cocoa powder, charcoal powder and hot water in another bowl into a paste in between.

Once your batter is well combined, portion out a third of the batter into another mixing bowl. Mix in your chocolate paste with the batter thoroughly.

Transfer half of the vanilla batter into the loaf pan. Then, transfer all of the chocolate batter for the second layer. Cover it with the rest of the vanilla batter as the third layer.

Using a fork, swirl the batter, go back and forth for a few times to make sure that the two batter are well marbled.

Bake it in the oven for about 1 hour and 15 minutes, toothpick inserted into the centre comes out clean.

Let cool completely before slicing it up. It can keep well for up to 5 days in room temperature.