1 ½ cups/330 g unsalted butter, softened to room temperature
1 ½ cups/180 g confectioner’s sugar
2 Tbsp runny honey or golden syrup
½ cup/50 g unsweetened Dutch-processed cocoa
¼ cup/60 ml boiling water
8oz/255 g semisweet chocolate chips (70% cacao or greater)
¼ cup/60 g sour cream
1 Tbsp bourbon (optional)
1 ½ tsp vanilla extract
1 Tbsp gold sugar pearls (optional)
- Place the butter in the bowl of a stand mixer and whisk on medium-high speed using the paddle attachment, until the mixture turns pale yellow, 3 to 4 minutes.
- Add the confectioner’s sugar and honey and whisk over low speed (or it will fly out). Once the white “dusty” sugar is no longer visible, increase the speed to medium-high, and beat till the mixture turns light and fluffy and pale white, 4 to 5 minutes.
- Stop the mixer and scrape the sides of the bowl down with a spatula. Add the cocoa and mix on low speed till combined, 2 to 3 minutes
- Fill a saucepan with about an inch/2.5cm of water and bring it to a simmer. Place a medium, non-reactive stainless-steel bowl over the saucepan, the water should not touch the bottom of the bowl. Add the boiling water and chocolate and stir with a silicone spatula till the chocolate completely melts. Remove from the bowl from the saucepan, fold in the sour cream, bourbon, and vanilla. Pour this mixture into the creamed butter mixture and whisk on medium speed till the mixture is completely combined, scrape the sides of the bowl down to ensure there are no unincorporated bits. Whisk on high speed till the mixture is fluffy. It might fall apart but it will eventually come together. Transfer the mixture to an airtight container, cover the surface with a sheet of clingfilm or parchment paper pressing down gently, refrigerate until ready to use.
- When ready to frost the cake, FIRST make sure the cake is completely cooled or chilled or by the buttercream frosting will melt. SECOND, warm the chilled frosting for at least 30 minutes to room temperature before applying it to the cake. Use an offset spatula to top the cake with the frosting.
- Decorate however you want to with the gold sugar pearls. You can use silver or skip it entirely (and yes, even use funfetti).
- This cake will be good for up to 3 days if stored in the refrigerator. You can also freeze it but remember to wrap it tightly with clingfilm ad keep it in an airtight container or it will dry out.