I just celebrated Christmas with my family in the rainy dales of Yorkshire. Luckily my uncle saved us from a christmas without chocolate, and sacrificed the bars he'd brought from Boston to make this cake.
8 eggs seperated
240gdark chocolate (70% or more)
2 tbsp good quality cocoa (not drinking chocolate!)
1 tin of creme de marrons (chestnut puree), preferably unsweetened
1 1/2 pints of double cream
Heat the oven to 160oc. Line a roulade tin (or other square or rectangular shallow bottomed tin) with paper and grease.
Melt the dark chocolate in a bain marie (double boiler). Meanwhile whisk the egg yolks with the sugar until doubled in volume and pale and fluffy. Let the chocolate cool, but not so much that it sets. Whisk the egg whites until they stand in peaks and you could, if you tried, hold the bowl of them upside-down over your head. Now fold the chocolate into the yolks and sugar, and then into the whites. Fold in the cocoa powder.
Spread evenly in the roulade tin and bake until the top is just risen at the middle and has formed a crust, the inside will still be gooey. Cover and leave to cool in the tin.
Whip cream until it just holds peaks, and fold in the creme de marrons, if unsweetened sweeten to taste.
Spread over the top of the cooled roulade, and using the paper underneath as a guide, roll the roulade into a log shape.
Dust with cocoa.