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 1/2 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.