Preheat a fan-forced oven to 140°C (275°F) or a conventional oven to 160°C (320°F). For this recipe you’ll need two 8” cake tins. Very lightly spray the bottom of each cake tin with cooking oil and line with baking paper. Set aside.
Run the cocoa powder and flour through a sieve into a mixing bowl. Use a whisk to combine. Set aside.
Add the eggs to the bowl of a stand mixer. You can make this recipe using an electric handheld mixer. If using a stand mixer fit it with a balloon whisk attachment. Whip on high speed for 1 minute until frothy. Then add the sugar while the mixer is on 1 tablespoon at a time until it’s all in the egg mixture. Mix on high speed for 8 minutes. The mixture will become thick and glossy.
Add 1/3 of the flour mixture and use a spatula to gently fold through the whipped egg mixture. Add another 1/3 and repeat until all of the flour is folded in. Just a note, take care to make sure you’re scraping all the way down to the bottom as you fold because the flour can sink to the bottom of the bowl.
Add the vanilla extract and lightly drizzle the melted and cooled butter with one hand as you gently fold it into the mixture.
Split the cake mixture amongst your cake tins and bake for 20-25 minutes. Allow to cool for 10 minutes before running a knife around the outside to loosen the cakes up from the tins. Transfer to a cooling rack to cool to room temperature. Once they have, use a large serrated knife or cake leveller to trim each cake in half, leaving you with 4 cake layers. Once you’ve made the syrup (in the next step) soak each cake layer in the cooled syrup by using a spread to evenly spread it around the cake.