Coffee - Kahlua Mousse

1. Melt chocolate and butter over a double-boiler.
2. Dissolve instant coffee in water.
3. In a large bowl, combine sugar, egg yolks, kahlua and coffee.
4. Foldi in the chocolate mixture.
5. Whipi cream until stiff peaks form; fold into kahlua-chocolate mixture.
6. Beat egg whites until stiff, then fold in the mixture.
7. Pour into serving cups.
8. Refrigerate for at least 4 hours.
9. Top with whipped cream and / or shaved chocolate.