Preheat the oven to 170°C. Butter and line a 23cm round springform tin with a disc of buttered baking paper. Lightly dust the inside of the tin with cocoa and then tip out excess.
Put the chocolate and butter into a medium-size heatproof bowl, add the ginger wine and set the bowl over a pan of barely simmering water. Stir occasionally until melted and smooth. Remove from the heat and cool slightly.
Tip both sugars into a large mixing bowl or the bowl of an electric mixer and add the egg yolks. Whisk until pale and light. Pour the melted chocolate and butter into the yolks and stir until smooth. With another large, spotlessly clean bowl and whisk, beat the egg whites with a pinch of salt until they just hold a stiff peak.
Sift the ground almonds and ginger into the chocolate mixture and fold in using a large metal spoon. Add one-third of the egg whites and stir in to loosen the mixture. Fold in the remaining egg whites until combined.
Spoon half the mixture into the prepared tin and gently spread level using a palette knife. Gently warm the ginger preserve, if using, until it’s just spreadable, then carefully spoon onto the cake in small dollops. Spoon over the remaining chocolate mixture and spread level. Bake just below the middle shelf of the oven for 50 minutes-1 hour until a wooden skewer inserted into the middle of the cake comes out with a moist crumb attached. Allow the cake to cool in the tin and don’t be dismayed if the top sinks and cracks.
To make the ganache, tip the chocolate into a heatproof bowl. Add the cream, butter and ginger wine. Set the bowl over a pan of barely simmering water and stir until melted and velvety smooth. Remove from the heat and allow to cool slightly.
Carefully run a palette knife around the edge of the cake to loosen it, then put on a serving plate. Spread the ganache over the top, and leave to set before serving.
Look for ginger preserve, or jam, at specialist food stores or at British food suppliers.
Article from the September, 2011 issue of Taste magazine.