There are many occasions, in my life, where a cake is needed at the last minute. Some cakes are elaborately decorated and require special ingredients – you couldn't just whip one up; it requires planning. This cake, though, is the perfect last-minute celebration cake. It uses ingredients you probably already have in the pantry – the buttercream doesn't even use any icing sugar.
This recipe comes from my best friend's grandmother. I've been using it for years, now. If you want, you can just throw all of the ingredients into the bowl of a stand mixer (in the exact order listed) and whisk for a couple of minutes until smooth. I like doing the alternating flour-milk method to avoid over-working the gluten in the flour.
The chocolate flavour is made even richer with the addition of hot coffee. The original recipe was much more frugal and used white sugar and boiling water. I think the coffee really highlights the chocolate flavour and, by using dark brown sugar instead of white, the cake is even more moist and has a slight caramelised flavour.
For icing, I love to make an Italian meringue buttercream. I think the buttery, creamy frosting works really well with the dense chocolate cake. It might take a few attempts to get this recipe right, but once you do, you won't look back - the flavour of the light and airy buttercream is superior to thicker icing sugar-based frostings and it's always the perfect texture for spreading onto the cake.
For the chocolate cake:
125ml vegetable oil or softened butter
250g dark brown sugar
1 tsp vanilla
1 tsp sea salt
50g cocoa powder
190g plain flour
1 tsp baking soda
1 tsp baking powder
125ml boiling water
For the Italian buttercream:
3 egg whites, room temperature
1/2 tsp cream of tartar
250g white sugar
1 tsp good quality vanilla extract or vanilla bean paste
250g/1/2 big block good quality butter
1. Make the cake: preheat your oven to 160°C. Grease and line a removeable-bottom cake pan (like a springform pan, about 20cm) with parchment.
2. Place the first six ingredients to a mixing bowl and whisk until everything is well-combined. Then, add half the dry ingredients. Mix slightly, then add the buttermilk and remaining dry ingredients. Mix to incorporate everything. Finally, add the hot coffee (it needs to be as close to boiling as possible). Mix well until you have a nice smooth batter.
3. Pour the batter into the prepared pan and bake for 40-60 minutes. When a toothpick inserted into the centre comes out clean, it’s ready.
5. Cool completely and slice in half before icing.
6. Make the Italian buttercream: in a small saucepan, combine the sugar and water. Bring to a boil and cook until it reaches about 110°C (if using a candy thermometer). I don't use a thermometer; I just keep an eye on the sugar. You don't want it to caramelise, but you do want it to be a thick syrup. Usually, at the point when the bubbles get smaller, this is the right time to take the sugar syrup off the heat.
7. While the sugar syrup is boiling, add the egg whites to the bowl of a stand mixer (using the whisk attachment). Add the cream of tartar to the egg whites and whisk until stiff peaks are formed, around five minutes.
8. When the sugar syrup is ready, put the stand mixer speed on low and slowly drizzle the syrup into the egg whites. The syrup will splatter on the sides of the bowl and harden if you aren't careful about the speed and location of the drizzle. Add all of the syrup to the egg whites, then increase the speed and whisk for another 5-10 minutes, until the mixture cools slightly.
9. Cut the butter into small cubes. When the sides of the stand mixer bowl feel cooler, set the speed to low again and slowly start adding the butter, cube by cube. As the butter becomes incorporated into the meringue mixture, it will deflate and look terrible. This is supposed to happen. Keep going!
10 Continue adding the butter, piece by piece, until the mixture thickens. This usually doesn't happen until the very last second, when you've used the last of the butter. It will get very thick and look a bit curdled – just increase the speed at the end and whisk until smooth, light and airy.
11. Mask the cooled cake with the Italian buttercream. You can serve the cake right away or keep it in an airtight cake container for up to three days before serving (I think it's actually better the following day, once the icing has firmed up a bit).