This is my Granny Sell's recipe. She never wrote it down before she passed away, so I've tried to copy it with trial and error. It is such a family favorite that I usually double the recipe when I make it.
Mix sugar,cornstarch, and salt in saucepan. Add milk. Cook and stir over medium heat until thick and bubbling. Cook and stir 2 minutes more, then remove from heat. Add a small amount of hot mixture to beaten egg yolks, then quickly add back to rest of mixture. Cook and stir for 2 more minutes, then remove from heat and add butter and vanilla.
Layer in serving bowl. I put 1/2 of grahams on bottom, 1/2 bananas next, 1/2 pudding mixture next. Repeat layers and add 1/4 cup graham crumbs on top for garnish. Makes 4 or 5 servings.
I usually make this in the morning, because it tastes wonderful after it has cooled all day in refrigerator and all the flavors marry. I also double this because there is never enough for all of my family.