Mix pudding, 2 cups milk and Cool Whip together. In a 9X13 pan, line with 12 graham crackers. Put 1/2 of pudding mixture over graham crackers. Put another layer of graham crackers, the rest of the pudding mixture, and another layer of graham crackers.
For Frosting Glaze
Mix melted chocolate, margarine, powered sugar, vanilla & milk together until smooth. Pour and spread over graham crackers.
Cover and refrigerate. Best if made the night before to allow graham crackers to soften.