In a heavy bottomed pot add cornstarch, sugar, salt and cinnamon. Very slowly add milk, mixing with a whisk vigorously to avoid cornstarch clumping. Begin heating on a medium low heat.
Stir constantly until mixture has thickened, about 5 minutes, add vanilla. Remove from heat and pour into a large bowl.
Place plastic covering directly on top of the pudding to avoid pudding skin to form.
Pudding will thicken considerably while cooling. Chill until ready to use.
Combine all caramel ingredients, except the salt, in a small pot on medium heat. Stirring regularly, bring mixture to a boil. Boil for 4 minutes, stirring constantly.
Remove from heat and allow to cool for 10 minutes then transfer to an 8 oz glass jar. If not using the same day, store in refrigerator for up to 2 weeks.
Place a layer of sliced bananas on the bottom of the crust. Drizzle with salted caramel. Add a layer of pudding. Repeat until filling fills the crust.
Refrigerate for at least 1 hour or until ready to serve. Once ready to serve, top with whipped cream, walnuts, and a caramel drizzle.