I was really excited when my sister-in-law asked me to provide the cake for my mother-in-law’s surprise birthday party last weekend. I’d been eyeing off this cake on Annie’s Eats for a long while, but without an occasion, it’s not the sort of cake you want just sitting on your kitchen bench staring at you seductively, especially when you’re trying to limit the decadent foods that enter your gullet.
My mother-in-law is not the easiest person to surprise because she’s really big on communicating. She’s always calling, trying to find out the nitty gritty details of various life events. Her and my sister-in-law speak on the phone several times a day, so it wasn’t easy for her to keep the details of the surprise away from her mother.
My mother-in-law also has a tendency to change her mind a bit. The day before the surprise party, she rang me to try and get me to come over to her place and head down to the restaurant early (the restaurant was the decoy plan). I was a bit non-committal, I didn’t want to raise too much suspicion with a flat out no. The following day she rang again, I made some excuse about having to do some gardening. She sounded dejected. She’d spent the afternoon baking a cake for the kids. Plus I’m a really bad liar in these situations.
Finally, all the guests were gathered at my sister-in-law’s house, huddled together in the lounge room. We got the call that they were on their way. We hushed and there was a quiet electric buzz amongst the guests. The phone rang once more – mother-in-law was changing her outfit. GAH!
In the end she was actually very surprised. I was so relieved that the plan had worked! She wasn’t disappointed that we weren’t having a fancy restaurant dinner and was happy to be amongst family and friends celebrating her birthday.
In any case, I was really pleased with the cake. I would say as a note, next time I make it I will make sure that the salted caramel swiss buttercream is actually pretty salty. It has to compete with a lot of sweet cake, so make sure you add a good helping of sea salt.
For the cake:
2¼ cups (250g) plain flour
2¼ cups (305g) caster sugar
1 cup plus 2 tablespoons (150g) dutch-process cocoa powder
2¼ tsp. bicarb soda
1½ tsp. baking powder
1½ tsp. salt
6 tbsp. (30mL) vegetable oil
1 cup plus 2 tbsp. (260mL) buttermilk
1 cup plus 2 tbsp. (260mL) brewed coffee (like a big long black or just make up using instant coffee)
3 large eggs, at room temperature
1 tbsp. vanilla extract
For the filling:
1 cup (225g) sugar, divided
¼ cup (60mL) water
¼ cup (60mL) thickened cream
Generous pinch of sea salt (to taste, I reckon around 2 heaped teaspoons at least)
4 large egg whites
340g unsalted butter, at room temperature
For the frosting:
340g dark chocolate, 70% cocoa solids, finely chopped
¼ cup (30g) unsweetened dutch-process cocoa powder
¼ (60mL) cup very hot water
250g unsalted butter, at room temperature
1/3 cup plus 1 tbsp.(50g) icing sugar
Pinch of salt
sea salt, for finishing
To make the cake, preheat the oven to 180˚ C. Grease and flour the edges of 3 20cm baking pans, shaking out the excess. Line the bottoms with rounds of baking paper. In the bowl of an electric mixer, combine the flour, sugar, cocoa powder, bicarb soda, baking powder, and salt. Mix on low speed to blend. Add the vegetable oil, buttermilk, coffee, eggs, and vanilla to the bowl and mix on low speed until well blended and completely incorporated. Divide the batter evenly between the prepared pans. Bake 20-25 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans about 15 minutes, then invert onto a wire rack and allow to cool completely. Remove the baking paper.
To make the caramel buttercream filling, place ½ cup plus 2 tablespoons (or 130g) of the sugar in a medium saucepan. Mix in the water. Bring the mixture to a boil over medium heat. Stop stirring and let the caramel cook, gently swirling from time to time, until it is a deep amber color (test a drop on a white plate or bowl if necessary), watching it carefully to avoid burning. Remove the mixture from the heat and slowly whisk in the cream and then the salt. Set aside and let cool.
Combine the egg whites and the remaining ¼ cup plus 2 tablespoons sugar in a heatproof bowl set over a pot of simmering water. Heat, whisking frequently, until the mixture reaches 71° C and the sugar has dissolved. Transfer the mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form and the mixture has cooled to room temperature, about 8 minutes. (The bowl should be cool to the touch.)
Reduce the speed to medium and add the butter, 2 tablespoons at a time, adding more once each addition has been incorporated. If the frosting looks soupy or curdled, continue to beat on medium-high speed until thick and smooth again, about 3-5 minutes more (or longer - don’t worry, it will come together!) Blend in the cooled caramel until smooth and completely incorporated, scraping down the sides of the bowl as needed.
To make the frosting, place the chopped chocolate in a heatproof bowl set over a pan of simmering water. Heat, stirring occasionally, until the chocolate is completely melted and smooth. Set aside and let cool to room temperature. In a small bowl, combine the cocoa powder and water and stir until smooth. In the bowl of an electric mixer, combine the butter, icing sugar and salt. Beat on medium-high speed until light and fluffy, about 5 minutes. With the mixer on low speed, gradually blend in the melted and cooled chocolate until well incorporated. Blend in the cocoa powder-water mixture until smooth.
To assemble the cake, level the cake layers if necessary. Place one of the cake layers on a cake board or serving platter. Top with half of the caramel buttercream and smooth in a thick, even layer. Place a second cake layer on top and smooth the remaining caramel buttercream over that. Place the final cake layer on top. Cover the top and sides of the cake with the chocolate frosting and smooth with an offset spatula. If desired, use additional frosting to pipe decorative accents on the cake. Refrigerate until ready to serve (though take it out of the fridge a few hours before, so that it has a chance to come back to room temperature). Before serving, sprinkle with sea salt.
(Thanks to Annie’s Eats for the recipe).