Preheat the oven to 350°F. Line a large baking sheet with parchment paper. 

In a large bowl, mash the bananas with a fork or potato masher. 

Stir the oats and peanut butter into the bananas until combined. Mix well. Optionally, stir in chocolate chips and maple syrup for sweetness. 

Before working with the dough, wet your hands to prevent the dough from sticking. Use a spoon or large cookie scoop to portion out 8 balls of dough. Use your hands to flatten the dough into round cookies about ½ inch tall.

Place the cookies on the baking sheet lined with parchment paper. Bake in the preheated oven for 12 - 15 minutes, until lightly browned. 

Let the cookies cool on the baking sheet for 10 - 15 minutes before transferring to a wire rack (or a plate) to cool completely.