Place the chocolate wafers in the bowl of a food processor and pulse until finely ground. (You should have about 2 1/4 cups crumbs.)
In a large bowl, stir together the chocolate crumbs and butter until thoroughly combined. Transfer the crumbs to a 10-inch (6-cup capacity) pie plate, and using the bottom of a cup, press the crumbs into the dish and up the sides to form the crust. Refrigerate crust while you prepare the filling.
In a medium saucepan over medium-low heat, combine the milk and sugar, stirring just until disolved. Whisk in the peanut butter and vanilla until mixture is smooth and creamy. Transfer the mixture to a large bowl.
Beat the well-chilled heavy cream in the bowl of a stand mixer fitted with the whisk attachment until stiff peaks form.
Fold the whipped cream into the peanut butter mixture.
Slice the banana into rounds and arrange them in a single layer on the bottom of the cookie crust.
Pour the peanut butter mixture over the bananas, smoothing with a spatula, and then top with the chopped salted peanuts.
Freeze pie, uncovered, until solid, about 5 hours. Slice and serve.