In a large mixing bowl, melt 1/2 cup of unsalted butter and let it cool slightly until creamy. Add 1 cup of brown sugar to the bowl, and mix together until well blended and smooth.

Stir in 1 mashed ripe banana, 1 egg yolk, and 1 teaspoon of vanilla extract. Mix until you achieve a smooth consistency.

Sprinkle in 1/2 teaspoon of baking soda, 1/4 teaspoon of salt, and 1 teaspoon of ground cinnamon, then mix until fully combined.

Gradually add 1 1/2 cups of all-purpose flour to the wet mixture, folding gently until no dry streaks remain in the dough. Then, fold in 1 cup of chocolate chips.

Cover the cookie dough with plastic wrap and refrigerate for 1 hour.

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

Once chilled, use a cookie scoop or tablespoon to portion the dough onto the prepared baking sheets, leaving at least 2 inches of space between each scoop.

Place the baking sheets in the preheated oven and bake for 10-12 minutes. They are done when the edges are golden brown and the centers are slightly soft.

Let the cookies cool on the baking sheets for about 2 minutes before transferring them to a wire rack.