This recipe was taken from Delia Smith’s Complete Cookery Course (1982), page 602.
150g caster sugar (azúcar fino)
6 large eggs, separated (6 huevos XL, separados clara/yema)
50g cocoa powder (cacao puro molido)
For the filling:
225g plain chocolate (chocolate Valor)
2 large eggs, separated (huevos enteros, separados clara/yema))
225ml double cream (nata espesa)
Icing Sugar (azúcar glás)
Pre-heat the oven to 180ºC.
Pre-heat the oven to 180ºC. Prepare a tin 29cm x 18cm and about 2,5cms deep, oiled and lined with greaseproof paper (papel vegetal), also lightly oiled.
Begin by making the chocolate filling. Break the plain chocolate in pieces into a basin and add 2 tablespoons of water. Now place the basin over a saucepan of barely simmering water and wait for the chocolate to melt. After that, remove from the heat and beat it with a wooden spoon until smooth. Next, separate two large eggs and beat the yolks, first on their own, then into the warm chocolate mixture. Let it cool a bit then whisk the egg whites till stiff and fold them into the chocolate mixture. Cover the bowl and chill in the fridge for about an hour.
Meanwhile you can get on with the cake. First place the egg yolks in a basin and whisk until they start to thicken, then add the caster sugar and continue to whisk until the mixture thickens slightly – but be careful not to get it too thick. Now mix the cocoa powder into the egg yolk mixture, then, using a clean whisk and bowl, beat up the egg whites to the soft peak stage. Next carefully cut and fold the egg whites into the chocolate mixture – gently and thoroughly – then pour the mixture into the prepared tin.
Bake the cake on the centre shelf for 20-25 minutes until springy and puffy. When the cake is cooked, remove it from the oven but leave it in the cake tin to cool (it will shrink quite a bit as it cools but don’t worry, that’s normal).
Then when the cake is quite cold, turn it out onto an oblong of greaseproof paper which has been liberally dusted with icing sugar. Peel away the cake tin lining paper from the bottom of the cake (which is now facing upwards), then spread the chocolate mousse filling over the cake. Next whip the cream softly and spread it over the chocolate filling. Finally, gently roll up the cake to make a log shape. This will serve 8 people and, although it’s unlikely that there will be any left, you can cover any remaining cake with an upturned basin and keep it in the fridge. As an alternative, you can replace the chocolate mousse with a tin of sweetened chestnut puré (crema de castañas).
Note: during the folding up, the cake will crack, but this is quite normal and looks most attractive.