Combine lemon instant pudding mix, whole milk, and fresh lemon juice in a mixing bowl. Whisk together until pudding is thick (about 2 minutes).
Spread 1 1/2 cups onto the prepared crust.
Beat the heavy whipping cream and powdered sugar in the bowl of a stand mixer, or with a handheld blender, until stiff peaks form. This takes about 5 minutes.
Add half of the freshly whipped cream into the remaining lemon pudding mix and whisk together until combined. Spread over the lemon pudding in the pie crust.
Top the pie with the remaining whipped cream.
Cover with the enclosed lid and let refrigerate for at least 3-4 hours before serving. For best results make the night before and let it sit in the fridge overnight.
If you don't want to whip your own cream simply use an 8 ounce tub of Cool Whip. Combine half of it with the remaining lemon pudding mix and the other half for the top layer of the pie.
To speed up whipping the cream, place the bowl and beaters in the freezer for about 15 minutes to get ice cold. The colder the better as it will speed up the process of whipping the cream (usually 2-3 minutes instead of 5 min or more).