Bake and cool the crust – Prepare a 9-inch pie crust and bake it until golden. Let it cool completely.
Make the custard – In a saucepan, whisk together sugar, cornstarch, and salt. Slowly whisk in milk. Cook over medium heat, stirring, until thickened (6–8 minutes).
Temper the yolks – Slowly add some of the hot custard into the egg yolks, whisking constantly. Pour back into the pan and cook for 2 minutes. Remove from heat and stir in butter and vanilla.
Add bananas – Mash 3 ripe bananas and fold them into the custard mixture. Let it cool slightly.
Whip egg whites – In a clean bowl, beat egg whites until soft peaks form. Add sugar gradually and beat until stiff peaks form.
Fold together – Gently fold the egg whites into the banana custard. This makes the chiffon texture.
Assemble pie – Place banana slices on the cooled pie crust. Pour the chiffon filling over them and smooth the top.
Chill – Refrigerate for at least 4 hours, or overnight, until firm.
Garnish and serve – Top with whipped cream, extra banana slices, and optional chocolate shavings. Slice and enjoy.