Ingredients (serves 8):

200 gram chocolate, at least 50% cocoa
40 gram butter
8 egg whites
6 egg yolks
30 gram sugar

Melt the chocolate together with the butter. Don't let the chocolate get too cold. Separate the eggs. Mix six egg yolks well with the sugar until it gets foamy. Beat the egg whites until stiff - but not too hard. Mix the chocolate with the egg yolks and sugar. Carefully fold in a few spoons of egg white. Then fold in the rest of the egg white carefully. Full the mousse into glasses or bowls. Leave to chill for at least three hours before serving.