Julia's Ultimate Chocolate Birthday Cake!

What’s not to love about chocolate cake? Universally loved for its decadent, rich base and creamy frosting, it pleases even the fussiest of birthday party-goers.

This one by Julia Busuttil Nishimura gives us all the nostalgic feels! The one-bowl, one-pan wonder is not only simple to whip up, but tastes utterly delectable. It’s sure to be your new go-to for birthdays and afternoon teas alike.

Julia Busuttil Nishimura

Julia’s go-to chocolate birthday cake! Photo – Eve Wilson for The Design Files.

The sheet pan cake is the simplest treat to whip up. Photo – Eve Wilson for The Design Files.

And finished with delectable chocolate cream cheese icing! Photo – Eve Wilson for The Design Files.

Julia Busuttil Nishimura
24th of October 2022

My chocolate buttermilk cake is simple, quick to make and happens to feed a crowd, which makes it my go-to cake for birthdays and celebrations. While a multi-layer cake is always impressive, I usually lean into something a little more approachable and there is nothing better than a cake that is baked in a rectangular cake tin. It’s super easy to decorate, easy to serve and I think it always looks great too. I’ve suggested 12 large squares but it can easily be stretched into 16 portions by reducing the serving size – after all it is rich and decadent.

And, I just love a cake that comes together in a single bowl with just a whisk. It means that from start to finish, it’s only really a few minutes of work. And while my kids would happily eat this cake for afternoon tea simply dusted with a little icing sugar (I mean, who wouldn’t?), for a celebration, it just has to have a generous swirl of the cream cheese frosting. Not too sweet, but luscious and light, the frosting is again, very simple to make. Here I ustilise a stand mixer for wonderful texture and ease. Just be sure that both the cream cheese and butter are at room temperature before beginning to mix to ensure the frosting is silky and smooth.

I do think sprinkles are rather sweet and a little bit of fun, but you can of course vary what you put on top of the cake. Freeze dried raspberries, or fresh for that matter, are lovely, as are cacao nibs or even just a sprinkling of sea salt flakes. The cake is best eaten on the day it’s made.

What birthday cake would be complete without rainbow sprinkles and candles! Photo – Eve Wilson for The Design Files.

Best eaten the same day! Photo – Eve Wilson for The Design Files.

This delicious cake can be cut into 12 or 16 serves. Photo – Eve Wilson for The Design Files.

Chocolate buttermilk cake with rich chocolate frosting

(Serves 12-16)

250 g caster sugar
100 g brown sugar
Pinch of sea salt
5 eggs
250 ml buttermilk
250g unsalted butter, melted and cooled
1 tsp vanilla extract
150 ml hot water
350 g self raising flour, sifted
100 g Dutch process cocoa powder, sifted
Sprinkles, to serve

Chocolate cream cheese frosting

250 g full fat cream cheese, at room temperature
150 g unsalted butter, softened
120 g pure icing sugar, sifted
50 g Dutch process cocoa powder, sifted
150 g 70% chocolate, melted and slightly cooled


Preheat the oven to 180C and grease and line a 30×20 cm rectangular deep cake tin.

In a large bowl, whisk together the sugars, salt, eggs, buttermilk, melted butter, vanilla and half of the hot water. Add in half of the flour and cocoa and gently whisk until just combined. Pour in the remaining hot water and whisk to combine. Finish with the remaining flour and gently whisk until just combined.

Pour the batter into the prepared cake pan and smooth the top with a spatula. Cook in the preheated oven for 30-35 minutes or until a skewer comes out almost clean when tested, a few crumbs are fine. Set aside to cool in the cake tin then transfer to a serving board or plate.

Meanwhile, for the frosting, place the cream cheese and butter in the large bowl of the stand mixer fitted with the paddle attachment. Beat on a high speed until smooth and light. Reduce the speed to medium and add the icing sugar and cocoa powder and continue to whisk. Stream in the melted chocolate and increase to the highest speed. Whisk the frosting until voluminous and airy (around 2-3 minutes). Use a palette knife or spoon to smooth the frosting over the cooled cake, creating a swirled pattern as you spread. Scatter with sprinkles or your desired decoration, cut into squares and serve

What else I’m cooking…

Enjoying the last of Spring things, like; asparagus gently poached in butter, lemon and water and eaten simply with boiled eggs and parsley; burrata with broad beans and mint and fried zucchini flowers stuffed with mozzarella and anchovy.

What I’m eating…

I recently returned from a beautiful week in Japan where we ate some really special meals. Always a favourite is the very special Monk in Kyoto, which is set just off the Philosopher’s path. Chef and owner Yoshihiro Imai centres the entire meal around the wood fire, including the most amazing pizza and highlighting seasonal vegetables from local farms. A must visit!

Click here to download the recipe printout!

Click here to download the recipe printout!

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