MIX gelatine, sugar and lemon zest in medium saucepan. Stir in 3/4 cup of the milk; let stand 1 min. Cook on low heat 5 min. or until gelatine is completely dissolved, stirring occasionally. Remove from heat. Add chocolate; stir until completely melted. Gradually add remaining 1-1/4 cups milk, stirring until well blended.
REFRIGERATE 30 min. or until mixture is consistency of unbeaten egg whites, stirring occasionally. Gently stir in whipped topping.
SPOON half of the gelatine mixture evenly into six 8-oz. parfait glasses. Top with the chopped cookies and remaining gelatine mixture. Refrigerate 2 hours or until set. Store leftover parfaits in refrigerator.