1. Preheat your oven to 350°F (175°C). Grease a 9×9 inch baking pan or line it with parchment paper for easy removal.
2. In a large mixing bowl, combine the mashed bananas, melted butter, granulated sugar, and brown sugar. Stir until well combined.
3. Add in the eggs and vanilla extract, mixing until the batter is smooth and the ingredients are fully incorporated.
4. In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.
5. Gradually add the dry ingredients into the banana mixture, stirring gently until just combined. Be careful not to overmix, as this can make the brownies tough.
6. Fold in the chocolate chips, ensuring they are evenly distributed throughout the batter.
7. Pour the batter into your prepared baking pan and spread it out evenly.
8. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs attached.
9. Allow the brownies to cool in the pan before cutting them into squares.

Just like my abuela taught me, trust your senses — the smell of these brownies as they bake is your best guide!