I grew up making PB&B by mashing the banana and peanut butter together in a bowl, tuning the ratio to taste at that time, and then applying the mixture to the bread. I'm starting to think maybe this was not the usual way?
I also mash the banana with peanut butter, but instead of putting it on bread, I put it on steel cut oats. Then add a small amount of milk and mix. Finally, top with honey.