Beat yolks and sugar into fluffy batter, until sugar is dissolved. Meanwhile, soak gelatine in small amount of cold water, heat it up, dissolve it and let it cool down. Pour little boiling water into cocoa to get thick mass and stir it into beaten yolks. Whip egg whites well. Stir everything together gently, pour in gelatine quickly stirring all the time. Pour into dessert cups immediately. Decorate with grated chocolate and whipped cream.