Place white chocolate and water in the top of a double boiler. Place pan over hot, but not boiling water and stir until chocolate melts. Remove from heat and stir in crème de cacao. Let cool.
Beat egg whites until soft peaks form, then gradually add sugar, beating until stiff and satin-like.
In separate bowl, whip heavy cream until soft peaks form.
Gently fold egg whites into the whipped cream.
Drizzle over and fold in the white chocolate mixture.
Spoon into small dessert cups (or dark chocolate cups); cover with plastic wrap and freeze.