Blend 3 pudding packages with 5 cups milk in a blender. Blend until completely smooth (about 2 minutes).
Mix in the sour cream. Using a chilled whisk, combine the ingredients. (I also do this with the blender.)
Place the vanilla wafers, banana, and half of the pudding mixture on a large baking tray (I’m using a 9×13 glass pan). Layer the waffle, banana, and remaining pudding mixture in the same manner. To end, I like to crumble the vanilla wafers on top. Refrigerate for at least one night.