Preheat oven to 375 degrees. Line two baking sheets with parchment paper or silicone baking mats, set aside.
In the bowl of a stand mixer or a large mixing bowl with a hand mixer, beat butter until creamy, about 2 minutes on medium speed. Add sugar and beat for an additional minute.
With mixing speed on low, add banana, egg, and vanilla extract. Mix until combined.
In a small mixing bowl, whisk together the flour, baking powder, and salt. With mixing speed on low, gradually add the dry ingredients to the wet ingredients. Mix just until combined. Fold in chocolate chips with a spatula or wooden spoon.
Using a standard size cookie scoop, scoop balls of soft dough onto the prepared baking sheets. Bake for 10-12 minutes or until the edges begin to brown. The cookies will be soft and muffin-like.
Remove from the oven and let cool for 5 minutes before transferring to a wire rack to cool completely.