Chocolate Mocha Cake

Lightly grease a deep 20cm|8" springform cake tin and line the base with non-stick baking paper.

For the base: mix together the biscuit crumbs and butter and press into the base of the tin. Chill while you make the filling.

For the coffee filling: Heat the cream and sugar in a pan over a low heat, stirring, until the sugar has dissolved completely. Remove from the heat.

Mix together the cornflour and water and stir into the mixture with the eggs. Return to the heat and bring to a boil, stirring constantly until very thick and smooth.

Remove from the heat and beat in the butter, vanilla and coffee until smooth and creamy. Pour half the filling over the chilled base and freeze while you make the chocolate filling. Cover the remaining coffee filling with a piece of damp non-stick paper and leave at room temperature.

For the chocolate filling: melt the chocolate in a heatproof bowl over a pan of simmering (not boiling) water. Remove from the heat.

Whisk together the egg yolks and cream until blended. Stir into the melted chocolate and whisk until smooth. Pour into a pan and heat gently, stirring constantly until thick enough to coat the back of a wooden spoon. Do not boil or allow to become too hot as the mixture will curdle. Remove from the heat and cover with a piece of damp non-stick paper and allow to cool completely.

Whisk the egg whites until soft peaks form. Gradually fold into the chocolate mixture until combined. Pour half the chocolate mixture over the coffee filling.

Whisk the remaining coffee mixture and carefully pour over the chocolate filling. Pour over the remaining chocolate filling and smooth the surface. Freeze for at least 3 hours or overnight.

To decorate: remove the cake from the freezer and allow to soften for 10-15 minutes at room temperature. Sprinkle the grated chocolate on top as well as pressing into the sides of the cake.