Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat. Set aside
In a large mixing bowl, mash the overripe banana until smooth.
Add the melted butter and packed light brown sugar to the mashed banana. Mix until well combined.
Stir in the egg yolk and vanilla extract, mixing until the ingredients are fully incorporated.
In a separate bowl, whisk together the all-purpose flour, ground cinnamon, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined. Be careful not to overmix.
Gently fold in the chocolate chips until evenly distributed throughout the dough.
Using a cookie scoop or spoon, drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden brown and the centers are set but still soft. The cookies will continue to firm up as they cool.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
