Recipe c/o the wonderful, fail-safe Delia Smith
For the cakes:
6 large eggs, separated
150g golden caster sugar
50g cocoa powder, sifted
For the filling:
400g pitted prunes, soaked overnight (or longer if possible) in 120ml Armagnac
1 level tablespoon crème fraîche
To finish:
150g dark chocolate (75 per cent cocoa solids), broken into pieces
1 level tablespoon crème fraîche
Pre-heat the oven to 350F/ 180°C. Grease 2 x 8″ (20cm) loose-based sandwich tins, 1.5″ (4cm) deep and line the bases with baking parchment.
Place the egg whites in a large, clean, grease-free bowl. Put the yolks in another bowl, along with the sugar, and whisk them until they just begin to turn pale and thicken – be careful not to thicken them too much; they need approximately 3 minutes’ whisking. After that, gently fold in the sifted cocoa powder.
With a clean whisk, beat the egg whites until stiff but not too dry. Using a metal spoon, fold a heaped tablespoon of the egg white into the chocolate mixture to loosen it up a little, then carefully and gently fold in the rest of the egg white, slowly and patiently trying not to lose any air.
Divide the mixture equally between the prepared sandwich tins and bake near the centre of the oven for 15 minutes. They won’t appear to be cooked exactly, just set and slightly puffy and springy in the centre, so when they’re taken out of the oven they will shrink (but that’s normal, so don’t panic). Leave the cakes to cool on a rack in their tins, then slide a palette knife around the edges, gently invert them on to a board and carefully strip off the base papers.
To make the filling for the cake, first of all set aside 10-12 of the largest prunes, then place the rest, plus any remaining soaking liquid, in a food processor, along with the crème fraîche, and whiz to a purée.
Place one of the cakes onto a serving plate and transfer the purée straight from the processor on to one half of the cake, then spread the purée out carefully and place the other half of the cake on top.
For the chocolate topping, place the broken-up pieces of chocolate in a large heatproof bowl, which should be sitting over a saucepan of barely simmering water, making sure the bowl doesn’t touch the water. Keeping the heat at its lowest, allow the chocolate to melt slowly – it should take about 5 minutes to become smooth and glossy. Then remove it from the heat and give it a good stir, then let the chocolate cool for 2-3 minutes.
Take each one of the reserved prunes and dip it into the melted chocolate so that half of each one gets covered. As you do this place them on a sheet of parchment paper to set. When all the prunes are done, stir the crème fraîche into the chocolate, then use this mixture to cover the surface of the cake.
Spread it over carefully with a palette knife, making ridges with the knife as you go. Decorate the cake with the chocolate prunes. Cover the whole thing with an upturned, suitably sized bowl or cake dome, and keep it in the fridge until about an hour before you need it.
NOTES:
Because the cake is flourless, it is good for coeliac guests, but apart from that it has a wonderful texture – not so much cakey as almost mousse-y. The Armagnac-soaked prunes mean that the cake is never too sweet and has a very definite grown-up feel to it, and it does look spectacular when it arrives at the table. I don’t think it needs to be served with anything, but if you insist, I would serve it with a little creme fraiche.