Combine cinnamon and sugar in a small bowl. Set aside.
Lightly spread butter on one slide of each slice of bread. Flip and spread peanut butter on the other side.
Heat large skillet or griddle over medium heat. Add 6 slices of bread, butter side down, on skillet or griddle (you may need to work in batched depending on size). Top with bananas and drizzle with honey. Place second slice of bread, peanut butter side down on top.
Cook for 3-5 minutes on each slide, or until lightly browned and toasty.
Remove the sandwich and while still hot, season liberally with cinnamon sugar.