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

In a large mixing bowl, combine the creamy peanut butter, mashed banana, brown sugar, and granulated sugar. Mix well until the ingredients are fully incorporated.

Add the egg and vanilla extract to the mixture. Stir until combined.

In another bowl, whisk together the baking soda, flour, and salt.

Gradually add the dry ingredients to the wet mixture, mixing until fully combined.

Fold in the semi-sweet chocolate chips until they are evenly distributed in the dough.

Using a tablespoon or a cookie scoop, drop rounded balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown. The centers may look slightly underbaked, but they will firm up as they cool.

Remove the cookies from the oven and allow them to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.