Ingredients
- 240g plain flour
- 160g caster sugar
- 160g light brown sugar
- 80g good quality cocoa powder
- 1 ½ tsp bicarbonate of soda
- 1 tsp baking powder
- 1 tsp salt
- 200g buttermilk (can be substituted with yogurt)
- 150g vegetable oil
- 2 eggs
- 2 tsp vanilla extract
- 15g instant coffee powder
- 200ml boiling water
- For the icing:
- 180g dark chocolate (60-70% cocoa)
- 150g butter, soft
- 150g sour cream
- 1 tsp vanilla extract
- 200g icing sugar
- 20g cocoa powder
- 1 tsp salt
- 1 tbsp malted milk powder (eg Ovaltine)
For my perfect chocolate cake, I went for a devil’s food-style sponge, which is rich and moist, but still light and well-balanced. For the icing, I opted for a classic chocolate buttercream with a little sour cream to balance the sweetness of the chocolate, and Ovaltine, which adds a subtle malty flavour.
1. Preheat the oven to 170 degrees. Line the base of two 7-inch or 8-inch tins with a disc of baking paper.
2. Whisk together the flour, sugars, cocoa powder, raising agents and salt in a large bowl. In a separate jug, whisk together the buttermilk, oil, eggs and vanilla. Pour the wet ingredients into the dry, and whisk to combine, making sure there are no dry ingredients at the bottom of the bowl. Dissolve the instant coffee powder in the boiling water, add to the bowl and whisk until homogenous.
3. Pour into the prepared tins, and bake for 30-40 minutes, until springy to the touch and a skewer inserted into the centre of the cake comes out clean.
4. Remove from the oven, and loosen the cake from the edges of the tin with a sharp knife. Cool in the tin for 10 minutes, then turn out on to a wire rack to cool fully.
5. Melt chocolate at 30 second intervals in the microwave until fully melted, then set aside to cool slightly. Beat the butter in the bowl of a stand mixer for three minutes until light and fluffy. Add the sour cream and beat to combine, scraping down the sides of the bowl to ensure it is fully homogenous. Sieve the icing sugar, cocoa and salt into the bowl and beat again until fully combined. Dissolve the malted milk powder in two teaspoons of boiling water, and add to the icing, then mix. Fold in the chocolate.
6. When the cakes have cooled, cut each in half horizontally. Place half of one cake on a plate or turntable, and spread a thin layer of buttercream on top with a palette knife. Place another half on top, and repeat until you have four layers of cake and three layers of buttercream. Use the rest of the buttercream to cover the top and sides, using the palette knife to create gentle waves and peaks all over. Serve immediately, or refrigerate for up to three days.
