Mix well margarine, pecans and graham wafer crumbs and pat into 9x13 inch (22x33 cm) pan. Bake at 350 degrees F (180 degrees C) till lightly brown, about 20 minutes. Cool completely. Beat together cream cheese, icing sugar and 1 cup (250 ml) of Cool Whip. Spoon onto baked layer. Mix both puddings with milk and beat as per package directions. Let pudding almost thicken and pour over second layer. Put remainder of Cool Whip on top and swirl melted chocolate throughout topping. This freezes well if kept tightly covered. Just cut off what you would like and keep the rest frozen.