Method

• Melt chocolate and butter in a bowl over simmering water (do not let the bowl touch the water). Cool 5 minutes.
• Whisk egg yolks with half the sugar until pale. Whisk in the warm chocolate.
• Whip cream to soft peaks. Fold gently into chocolate mixture in two batches.
• In a clean bowl whip egg whites with salt to soft peaks, then add remaining sugar and whip to firm glossy peaks. Fold into chocolate mixture a third at a time, keeping as much air as you can.
• Divide into 6 glasses or ramekins. Cover and chill 2 hours.
• Serve cold with a small cloud of whipped cream and some shaved chocolate on top.