Put all of the vanilla wafers in a food processor fitted with a metal blade and process until the wafers are crumbs. Add the melted butter and pulse to thoroughly combine the crumbs and butter.
Pour this crumb mixture into a nine-inch pie plate and firmly press the mixture down onto the bottom and up the sides of the pan. You can use the bottom of a glass with a smooth surface to help press everything down evenly.
Bake the crust for 10-12 minutes or until it has lightly browned. Remove and place on a wire rack. Let cool for 30 minutes.
Arrange the banana slices on the cooled pie crust and set aside.
To make the Vanilla Custard, combine the sugar, flour, egg yolks, eggs, and milk in a medium-size saucepan over medium-low heat. Whisk constantly until the custard thickens, this should take from 8-10 minutes. The mixture should be thick and hold soft peaks when the whisk is lifted. Blend in the vanilla extract or vanilla paste.
Pour this mixture over the vanilla wafer crust and bananas. Smooth the surface and set aside.
Beat the egg whites with an electric mixer fitted with a whisk attachment on medium until they are white and frothy. Increase the speed to high and begin slowly adding the sugar, about a tablespoon at a time. Continue beating the egg whites until stiff peaks form and the sugar has dissolved.
Spread the meringue evenly over the pie and seal the edges.
Bake at 350 for 10-12 minutes or until the meringue is golden brown. Remove from the oven and let cool for 1 hour on a wire rack. Chill for 4 hours before serving.