Place half-and-half and pudding mixture in the bowl of a stand mixer and mix at low speed for 30 seconds. Increase speed to high and beat for 1-2 minutes.
Add 8 ounces of Cool Whip and mix on low speed until mixture is well blended. Fold in lemon zest.
Pour pudding mixture into prepared pie crust.
Spread remaining Cool Whip on top of lemon pudding mixture. Freeze pie for at least 2 hours.