In a medium saucepan, combine the sugar, flour, and salt. Gradually whisk in the milk until smooth.

Place the saucepan over medium heat and cook, stirring constantly, until the mixture thickens and starts to bubble, about 10 minutes.

In a small bowl, lightly beat the egg yolks. Gradually whisk about 1/2 cup of the hot pudding mixture into the egg yolks to temper them.

Pour the tempered egg mixture back into the saucepan with the rest of the pudding and whisk well. Continue to cook for another 2-3 minutes, stirring constantly, until the pudding is thick and creamy.

Remove the saucepan from heat and stir in the vanilla extract. Allow the pudding to cool slightly.

In a large serving dish or individual cups, assemble the banana pudding by layering vanilla wafers, banana slices, and pudding. Repeat layers until all ingredients are used, finishing with pudding on top.

If desired, top the pudding with whipped cream or meringue for added texture and sweetness.

Chill the banana pudding in the refrigerator for at least 2-3 hours before serving to allow the flavors to meld and the wafers to soften.