In a large mixing bowl, combine 1/4 cup of mashed overripe banana with 1/3 cup of melted butter or vegetable oil and 1/2 cup of light brown sugar. Mix thoroughly using a whisk or a fork until the ingredients are well blended and smooth, creating a cohesive batter that highlights the delightful banana flavor.

Stir in one egg yolk and 1 teaspoon of vanilla extract into the banana mixture. Mix until everything is fully incorporated, ensuring a rich and velvety texture.

Gradually sift in 1 cup of all-purpose flour, 1/2 teaspoon of baking soda, a pinch of salt, and 1/2 teaspoon of ground cinnamon, if using. Gently fold the dry ingredients into the wet mixture using a spatula until just combined—take care not to overmix.

Once the dough is ready, fold in 1/2 cup of chocolate chips with a spatula until evenly distributed throughout the cookie dough.

Let the cookie dough rest for about 15 minutes at room temperature to allow the flavors to meld.

Preheat your oven to 350°F (175°C) to achieve a perfect bake.

Using a cookie scoop or tablespoon, scoop 1-inch balls of dough and place them on the prepared cookie sheet, spacing them about 2 inches apart.

Bake the cookies in the preheated oven for 10 to 11 minutes, or until the edges are set and they have a slight golden tint.

Once baked, remove the cookie sheet from the oven and allow the cookies to cool for a few minutes before transferring them to a wire rack.