Add the softened butter into a mixer and mix for 2-3 minutes. Then add in the sugars and again, mix for a few minutes. Add the eggs into the butter mix one at a time.
Measure out the buttermilk into a jug and also add in the vanilla extract. Then add this into the butter mix. It can look very odd at this point but I promise it will all come together once flour is added. While it is mixing, weight out all your dry ingredients into a separate bowl. This is the flour, cocoa, baking powder and bicarb. Add in a spoonful at a time into the mixer.
Last of all, melt the dark chocolate in the microwave. Its best to do this 10-15 seconds at a time so it doesn’t burn. Pour this into the batter and mix by hand until combined.
Split this into 3 x 6 inch round tins. It is quite a thick batter so spread it out in the tin and leave a dip in the center of the tin to allow for rising. Cook at 160 fan for around 40 minutes or until cooked.
To make the buttercream –
Add softened butter into a mixer and mix on high for 4-5 minutes, scraping down a few times.
Add in the icing sugar and mix again for a further 5 minutes. Pour in your melted chocolate. Try not to lick the bowl too much!
To Decorate – Level and stack your cake with buttercream in the layers. Cover the cake in a thin layer of buttercream then scrape smooth. Put the cake in the firdge for 30 minutes to chill. You can grab my Perfect Buttercream Class as it will help you loads with this.
Pop both the cream and chocolate in a bowl and microwave on high for 20 seconds. Take out and stir well until melted. Put this chocolate ganache into a piping bag and snip a little off the end. Pour in small sections over the edge of your cake. Finish off with buttercream swirls and sprinkles.