Combine watr and 2 TB sugar in a small heavy saucepan; bring to a boil, and stir until sugar dissolves. Remove from heat, add chocolate, and cover. Let mixture stand 5 mintues or until chocolate melts. Cool.
Beat egg whites (at room temperature) until foamy. Add cream of tartar and 2 tB sugar, 1 TB at a time, beating until stiff peaks form. Set aside.
Add egg yolks to chocolate mixture; beat until smooth. Stir in Amaretto. Fold abotu 1/4 of the egg white mixture into chocolate mixture; fold chocolate mixture into remaining egg white mixture. Spoon mousse into 2 dessert dishes and chill. To serve, garnish each serving with an almond slice, if desired.