Chocolate nutty fudge cake

Ingredients List

Makes 1 cake
350 g plain chocolate, chopped
175 g unsalted butter, diced
55 g cocoa powder, sifted, plus extra for dusting
5 large eggs
1 teaspoon real vanilla essence
250 g golden caster sugar
100 g mixed nuts, roughly chopped (such as macadamias, pecans, walnuts, almonds, hazelnuts, pistachios)
icing sugar, for dusting
a springform pan, 22 cm diameter
greased and base-lined

Put the chopped chocolate and diced butter in a heatproof bowl set over a pan of steaming, not boiling, water. Stir frequently until melted and smooth. Remove the bowl from the heat, stir in the cocoa and let cool.
Meanwhile, put the eggs, vanilla essence and sugar in a large heatproof bowl and whisk briefly until frothy. Set the bowl over a pan of steaming water - the water should not touch the base of the bowl. Using an electric hand whisk, whisk the mixture until it is very pale and thick - when the whisk is lifted it should leave a visible ribbon-like trail.
Remove the bowl from the heat, and whisk for a couple of minutes so the mixture cools. Using a large metal spoon, carefully fold in the cooled chocolate mixture, followed by the nuts. When thoroughly combined, spoon the mixture into the prepared springform pan and smooth the surface.
Bake in a preheated oven at 180°C (350°F) Gas 4 for about 35 minutes or until firm to the touch but moist inside (do not overcook or the cake will be dry and hard to slice).
Remove from the oven and let cool in the pan. Unclip the pan, turn out the cake and serve, dusted with icing sugar and cocoa. Store in an airtight container and eat within 1 week. It does not freeze well.