Meanwhile, to make mousse, in 2-quart saucepan, mix 1/4 cup of the whipping cream, the granulated sugar and 1/3 cup liqueur. Cook over medium heat, stirring constantly, until sugar is dissolved and mixture simmers; remove from heat. Stir in chocolate chips with whisk until chips are melted. Stir in 2 teaspoons vanilla. Pour into large bowl; cool to room temperature, about 10 minutes.