Sprinkle gelatine over milk in medium saucepan; let stand 1 min. Cook on low heat 3 min. or until gelatine is completely dissolved, stirring constantly.
Add chopped chocolate; continue cooking until chocolate is completely melted and mixture is well blended, stirring constantly. Blend in vanilla.
Place saucepan in large bowl of ice water. Stir chocolate mixture 3 min. or until slightly thickened.
Pour into large bowl. Gently stir in whipped topping. Spoon evenly into 12 dessert glasses.
Refrigerate 4 hours or until chilled. Store leftovers in refrigerator.
