• Making time 30 minutes
• Preparation time  20 minutes

Ingredients

• 125 g caster sugar
• Four eggs
• 100 g self-rising flour
• 25 g cocoa powder
• 40 g unsalted butter, melted
• One teaspoon of vanilla extract

For the icing:

• 375 g plain dark chocolate, broken into pieces
• 250 g unsalted butter
• 100 g icing sugar, sifted

The snake which cannot cast its skin has to die, as well the minds which are prevented from changing their opinions; they cease to be mind.

– Friedrich Nietzsche

Preparation:

1. Put the sugar and eggs in a heatproof bowl set over a saucepan of gently simmering water, whisk, using an electric whisk, for 5-10 minutes until very thick and foamy and the whisk leaves a trail when lifted above the mixture.
2. Sift over the flour and cocoa powder and carefully fold into the mixture with the melted butter and vanilla until well combined.
3. Pour the mixture into an oiled and base-lined 20 cm spring-form cake tin and bake in a preheated oven, at 1800C, set the timer for 25 minutes until risen and firm to the touch. Remove from the oven and leave to cool in the tin for 15 minutes turn out on a wire rack and leave to cool.
4. Make the icing, and melt the chocolate and butter together in a heatproof bowl set over a saucepan of gently simmering water. Remove from the heat and beat in the icing sugar, set aside to cool and then chill for an hour until thickened, beat until pale and fluffy.
5. Slice the cake in half horizontally and use half of the icing to sandwich the halves back together, use the remaining icing to cover the top and sides of the cake, swirling the mixture with a palette knife.