Chocolate Mousse

Place chocolates, 1/4 cup sugar and water in a heatproof bowl and place over a pot of simmering water. Stir until the chocolate melts and the mixture is smooth. Remove from simmering water and whisk in egg yolks. Place back over the simmering water and stir continuously until the temperature reaches 160 degrees, about 8 minutes. Transfer to a large bowl and refrigerate for 20 minutes. Stir occasionally while it cools to make sure it cools evenly. The mixture should be at 110 degrees. Place egg whites and cream of tartar in a large mixer bowl and beat until soft peaks form. Slowly add 1/3 cup sugar, 1 tablespoon at a time. Remove cooled chocolate mixture and whisk about half the egg whites into the chocolate. Use a rubber spatula and fold in the remaining egg whites. Put the whipping cream, vanilla and coffee into a large mixer bowl and beat until soft peaks form. Fold whipping cream mixture into chocolate and pour into serving dishes.