Sprinkle gelatin over cold water in a small saucepan, let stand 1 minute. Cook over low heat, stirring constantly, about 2 minutes or until gelatin dissolves. Remove from heat; let cool.
Add cocoa and chocolate syrup to gelatin mixture, stirring with a wire whisk until smooth. Fold in 2 cups whipped topping. Spoon evenly into 6 individual dessert dishes. Cover and chill 2 hours or until firm.
Before serving, top each serving with 2 tablespoons whipped topping.