Before you begin, it’s really important to make sure the butter is soft enough. Some people keep their butter out of the fridge, others chill it. Even if you keep it out, it may not be soft enough. You want your butter to be soft enough so that when you stick your finger in it, it glides in, but not without a little bit of resistance. The best way to get it too that softness is to place your butter on a microwave safe plate, microwave for 10 seconds at a time, testing the softness each time. If it needs longer than 10 seconds, turn the butter over and repeat until it’s ready.
Add the softened butter to the bowl of a stand mixer fitted with the paddle attachment. You can also use an electric hand mixer for this recipe, but if you do use a hand mixer, just make sure your bowl is large. Mix the butter on low speed to begin with, then switch to the highest speed and mix for 5 minutes until the butter is fluffy and turns pale in colour.
Stop your mixer and scrape down the side of the bowl using a spatula. Add the icing sugar and vanilla extract and mix again on low speed. LOW SPEED PEOPLE! The last thing you need is to end up in a sugar dust storm! (I’m speaking from experience…)
Once all the sugar has been incorporated, it’s safe to turn your mixer up to high speed. Continue beating on high speed for about 5–6 minutes, or until the butter turns pale in colour and becomes fluffy again. If you want to soften your buttercream and make it a little smoother, add the milk and continue mixing for another couple of minutes on medium speed.
Preheat a fan-forced oven to 160°C (320°F) or a conventional oven to 180°C (350°F). Spray an 8” half sphere cake tin with oil spray and line with baking paper. Place on top of a 6” cake tin and then on a baking tray. Set aside.
Add the flour, sugar, cocoa powder, bicarbonate of soda and salt to a large mixing bowl and mix with a hand mixer until well combined.
Next, add the softened butter and mix on low speed until the batter reaches a crumbly, sand-like texture.
Add the eggs and milk and mix again on low speed until all the dry ingredients are incorporated. Scrape down the side of the bowl and mix for another 20 seconds. It’s at this point that you can add any additional flavourings or food-gel colourings to the batter.
Pour the batter into the prepared cake tin. Bake for 90 minutes, or until a toothpick inserted in the middle a cake comes out clean. If the toothpick is coated with wet batter, continue baking, for 10 minutes at a time, until fully baked.
Once cooled, take the cake out of the cake tin and trim the bottom of the cake.
Add a dab of frosting onto an 8” cake board or flat serving plate. Use a small offset spatula to spread the frosting around before adding the cake on top. Gently press down the centre of the cake layer to make sure it’s stuck to the frosting underneath.
Add frosting to a piping bag and frost around and top and sides of the cake. Use the small spatula to smoothen out the top and sides of the cake.
Use a cake scraper (otherwise known as a bench scraper) to smoothen out the frosting on the sides and top. Get it as neat as you can. This should just be a neat, thin layer of frosting which is aimed at trapping any cake crumbs so that random bits of cake crumbs don’t show up on the final layer of frosting. Chill for 2 hours or overnight.
Add a final layer of cake around the sides of the cake, Use the offset spatula to smoothen out. Pipe a neat ring of frosting on top of the cake. We want this to act as the lip around the top of the bowl. Use the spatula to smoothen out the sides, top and inside of the lip. Finish the cake by filling it with your favourite cereal.