1. Preheat the Oven:  

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or lightly grease it to prevent the cookies from sticking.

2. Prepare the Wet Ingredients:  

In a large bowl, mash the ripe bananas with a fork until smooth. Add the egg, vegetable oil (or melted butter), and vanilla extract (if using). Stir to combine.

3. Mix the Dry Ingredients:  

In a separate bowl, mix the brownie mix and baking powder (if using). Stir well to ensure all ingredients are evenly distributed.

4. Combine Wet and Dry Ingredients:  

Gradually add the dry ingredients to the banana mixture. Stir until fully combined. If you’d like, add chocolate chips or other mix-ins like nuts at this stage.

5. Form the Cookies:

Using a spoon or cookie scoop, drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart. The dough will be a little thicker than typical cookie dough, so don’t worry if it’s slightly sticky.

6. Bake:  

Bake for 10-12 minutes or until the edges are slightly golden, and the center is set. Keep an eye on them, as they can cook quickly.

7. Cool and Serve:  

Once baked, remove the cookies from the oven and let them cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.