1/2cupor 1 stick (115 grams) unsalted butter, room temperature
3and 1/2 cups (435 grams) powdered or icing sugar
4tablespoonsmilk
1/4cup(20 grams) cocoa powder
2/3cup(100 grams) milk chocolate, pieces
1/4cup(40 grams) milk or dark chocolate chips
Instructions
Preheat the oven to 360 F (180 C). Grease and line a round 8 inch springform cake tin with baking or parchment paper. In a large mixing bowl, sift the flour, cocoa powder, baking soda, baking powder and then add the sugars. Pop the butter into the microwave for short bursts, 10 seconds or so at a time, until it is just melted. Give it a stir with a fork to eliminate any lumps. Whisk together the butter, eggs, vanilla and buttermilk until combined – don’t worry if it goes a little lumpy. Then add the wet mixture into the dry mixture and gently fold until just combined.
Spoon the mixture into the prepared tin and pop into the oven. Bake for 25 minutes or until a skewer inserted into the middles comes out clean. Leave to cool for 10 minutes. Gently run a knife around the edge of the cake before turning out of the tin. Leave to cool completely on a wire rack.
To make the chocolate frosting, add the butter to a large mixing bowl and beat with an electric mixer until pale and creamy. Gently sift in the icing sugar, one cup at a time. Add a tablespoon or two of milk to help loosen up the mixture. Add the cocoa powder and beat again. Add the final two tablespoons of milk until the frosting is nice and creamy.
Frost the top of your cake with the chocolate buttercream. Then scatter over your pieces of chocolate and chocolate chips. Cut and serve.