In a food processor, pulse vanilla wafer cookies until finely crushed.
Add sugar and melted butter, and pulse until the mixture sticks together.
Press the mixture into the bottom and sides of a 9-inch pie plate. Chill for 1 hour.
In a large bowl, whisk together the banana pudding mix and milk until smooth. Pour the pudding mixture into the chilled crust and let it sit for 5 minutes to thicken.
Layer sliced bananas on top of the pudding.
Spread whipped topping over the entire surface of the pie.
Refrigerate the pie for at least 1 hour, then decorate with extra vanilla wafers before serving.