1. Stir together sugar and gelatin in small saucepan; stir in milk. Let stand 2 minutes to soften gelatin. Cook over medium heat, stirring constantly, until mixture just begins to boil.
2. Remove from heat. Immediately add chocolate chips; stir until melted. Stir in vanilla; cool to room temperature.
3. Beat whipping cream in small bowl until stiff; gradually add chocolate mixture, folding gently just until blended. Spoon into serving dishes. Refrigerate. Garnish with sweetened whipped cream, if desired. 4 to 6 servings.