Scald the milk. Mix the sugar, cornstarch and salt and add to hot milk, stirring rapidly and cook until thickened. Beat the eggs. Add a little of the hot liquid to the eggs, then add them to the thickened mixture. Cook 3 to 5 minutes. Add butter and vanilla. Cool, stirring once only after 5 minutes. Slice bananas on bottom of baked, cooked pie crust. Place half of pie filling on top of bananas. Add another layer of sliced bananas and place remaining pie filling on top of bananas. Garnish with bananas and whipped cream.