Grease a 8" pan with butter. Preheat oven to 350 degrees F.
In a food processor add the graham crackers and pulse them a couple of times to make a fine powder. Alternatively put them in a zip lock bag and crush with rolling pin.
Transfer the crumbs in a bowl. Add powdered sugar and melted butter. Mix well until combined.
Pour the crumbs mixture into the pie pan and press them gently from all sides and bottom.
Bake it in the preheated oven for 10 minutes.
Remove from the oven and let it cool.
In a mixing bowl, add condensed milk and evaporated milk. Whisk to combine. Add the lime zest.
Pour the filling into the cooled pie crust and bake it in the preheated oven for 12 to 15 minutes or until filling is set.
Remove from oven let it cool. Place the pie in refrigerator for 1 to 3 hours.
Remove from refrigerator. Top with whipped cream. Garnish with more lime zest .
Slice and enjoy.