Place the vanilla cookies in a food processor, and blend on high speed.
Reduce the speed to low, and slowly pour in the melted butter.
Grease a 9 inch pie dish with butter or vegetable shortening. Press the cookie crumbs firmly into the bottom and up the sides of the dish. Set in the freezer for 25 minutes.
For the pie filling:
Whisk together the instant pudding mix and cold milk in a large bowl.
Add the thawed whipped topping, and fold everything together until just combined.
Remove the crust from the freezer, and place the slices of banana in a single layer along the bottom.
Spoon the pudding mixture over the bananas, and spread evenly with a spatula.
Place the pie in the refrigerator for at least 4 hours.
Top with whipped cream and fresh banana slices, optional, and serve chilled. (For an easier slice, freeze the pie for an hour before serving.)
Notes
Banana Cream Pie can be made up to 3 days in advance.