In a medium saucepan, whisk together egg yolks, sugar, cornstarch, and salt. Slowly whisk in milk and vanilla bean, ensuring that the mixture is smooth and free of lumps.
Cook over medium heat, stirring constantly, until it comes to a simmer and begins to thicken, about 5 to 7 minutes. Remove from heat, and whisk in butter and vanilla.
Strain the pudding into a bowl and cover with plastic wrap, pressing it directly onto the surface of the pudding so that a skin does not form. Set aside and cool completely.
Prepare Whipped Cream
Combine all the ingredients in the bowl of an electric mixer fitted with the whisk attachment. Beat until stiff peaks form.
Fold half of the prepared whipped cream into the cooled pudding, and set aside the remaining half for topping.
Assemble
In a large serving dish (or individual dessert cups), place a layer of vanilla wafers. Top with a layer of sliced bananas, followed by dollops of prepared pudding. Repeat layers. Top with reserved whipped cream and garnish as desired.
Banana pudding must be kept refrigerated until ready to serve.