Combine vanilla pudding mix, milk, peach flavoring, and lemon peel in a saucepan.
Stir to dissolve pudding mix.
Cook and stir over medium heat until mixture comes to a full boil.
Set aside and allow to cool for 5 to 10 minutes.
Pour into prepared pastry shell.
Refrigerate until set.
Meanwhile, remove pits from peaches and peel them.
Slice each peach into 12 slices.
Soak in lemon-juice water until ready to use.
When filling is thoroughly set, remove peaches from lemon water, pat dry with paper towels, and arrange peach slices on top of pie.