Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone mat.
In a medium bowl, mash the ripe bananas with a fork or potato masher, leaving a few small lumps for texture.
In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon (if using).
In a large bowl, mix together the melted butter and brown sugar until smooth.
Add the mashed bananas, egg, and vanilla extract to the butter mixture and mix until well combined.
Gradually add the dry ingredients to the wet ingredients, stirring just until combined. Be careful not to overmix.
Fold in the chocolate chips (or any optional add-ins).
Scoop dough into balls and place them on the prepared baking sheet, spacing them about 2 inches apart.
Bake for 12-15 minutes, or until the edges are golden and the cookies have set.
Let the cookies cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.