Double cream – 2 cups
Caster sugar – 2/3 cup
Cocoa powder – 1/2 cup
Eggs, separated – 4
Rum or Brandy – 3 tbsp (Optional)
Icing sugar – 3 tbsp
Cashewnuts or hazelnuts, roughly chopped – 150 g
Line a 9 x 5 inch loaf tin with strips of foil or clingfilm with an overhang on the sides.
Heat 3/4 cup of the cream in a saucepan. In a bowl, mix caster sugar, cocoa powder and egg yolks. Pour hot cream on top and mix well. Pour back into the saucepan and cook over low heat, stirring continuously, until the mixture is thick enough to coat the back of a wooden spoon. Do not allow it to boil. Stir in the rum or brandy (if using) and remove from the heat. Cover the surface with clingfilm and cool for 30 minutes.
Whip the egg whites in a clean dry glass bowl until stiff peaks form.
Whip the remaining cream in a large bowl until soft peaks form.
Add the icing sugar and whip until stiff and glossy. Lightly fold the chocolate custard into the cream, then fold in the egg whites. Gently fold through the chopped hazelnuts. Transfer into the tin, smooth the surface and cover with cling film. Freeze for at least 24 hours. Leave at room temperature for 5 minutes before serving in slices.