• Preheat the oven to 160 °C. Grease and line a 15 x 30cm cake tin with baking paper.
• Combine the sugar, chocolate, butter and 180 mL of water in a saucepan and place over a low heat. Stir occasionally until the chocolate has melted and the mixture is smooth. Remove from the heat and allow to cool for 10-15 minutes.
• Add in the sifted flour, sugar and bicarb and whisk until smooth.
• Whisk in the buttermilk and egg and mix until smooth.
• Pour the cake batter into the prepared cake pan. Bake at 180 °C for 45 minutes, or until a skewer inserted into the middle comes out clean. Cool in the pan/

Cake Frosting

• Melt the chocolate in a bowl over a saucepan of simmering water, stirring occasionally, until smooth. Cool the chocolate until it's lukewarm.
• Add the chocolate and butter to a stand mixer and beat until fluffy.
• Beat in the icing sugar and buttermilk and mix until smooth.
• Spread over the cooled cake and serve.