Whisk: In a large bowl, whisk the two packages of vanilla pudding with the milk until the mixture is smooth and well combined.
Fold: Gently fold in the thawed Cool Whip using a spatula until no white streaks remain.
Flavor: Add the peppermint extract and the green food coloring. Continue to stir gently until the color is uniform and the mint is fully incorporated.
Fill: Pour the green mixture into the pie shell and smooth the top with a spatula.
Set: Refrigerate for at least 8 hours or overnight. This ensures the pudding sets firmly enough to slice.