Crumble 300 g of dark chocolate and melt the pieces together with 150 g of crème fraiche, stirring constantly over low heat or in a water bath. Stir in 2 tablespoons of coffee and let the cream cool a little. Then beat 4 egg whites until stiff and pour in 3 heaped tablespoons of powdered sugar.
First mix 2 tablespoons of chocolate cream into the egg white mixture, then fold in the rest with a whisk. Put the mixture in the refrigerator for at least 2 hours, or preferably overnight.