In a large mixing bowl, whisk together ½ cup of cooled, melted butter and 1 cup of packed brown sugar until smooth and creamy, about 1-2 minutes.

Add in ⅓ cup of mashed banana, 1 egg yolk, and 1 teaspoon of vanilla extract. Mix thoroughly for about 1-2 minutes until blended and thick.

Sprinkle in a pinch of salt, 1 teaspoon of baking soda, and 1 teaspoon of cinnamon into the mixture. Stir gently until well combined.

Gradually fold in 1 and ¾ cups of all-purpose flour until no dry streaks remain, then add in 1 cup of chocolate chips.

Cover the dough and refrigerate for at least 1 hour to maintain shape while baking.

Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.

Use a cookie scoop to portion dough onto prepared baking sheets, spacing them 2 inches apart.

Optionally press extra chocolate chips into the tops of the dough balls before baking.

Bake for 10-12 minutes until edges are golden and centers are soft.

Allow cookies to cool on baking sheets for about 2 minutes, then transfer to a wire rack to cool completely.