Preheat oven to 350 degrees and line a baking sheet with a silpat liner
Place banana into a mixing bowl and mash with a fork. Add finely ground graham crackers, chips and marshmallow bits, stirring to combine. With a cookie scoop, scoop dough onto prepared baking sheet. Press each cookie flat. Bake for 13-15 minutes until baked through. Let cool on baking sheet for 10 minutes before transferring.