Zest lemon into a large mixing bowl, being careful to avoid the white pith.
Cut the lemon in half and squeeze the juice into bowl. Check to be sure no seeds have fallen in.
Pour the milk into a large mixing bowl.
Add the pudding mix to the bowl.
Mix with a wire whisk for 2 minutes or until thick.
Fold in the Cool Whip with a spatula.
Spoon the pudding mixture into the crusts. Smooth with a butter knife.