01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or grease lightly with cooking spray.
02 - In a large mixing bowl, mash bananas until smooth. Add eggs, vegetable oil, brown sugar, and vanilla extract. Whisk thoroughly until fully incorporated and mixture is uniform.
03 - In a separate medium bowl, whisk together flour, baking powder, baking soda, and salt until evenly distributed.
04 - Pour dry ingredients into wet mixture. Fold gently with a spatula just until flour disappears—stop immediately when combined to prevent tough muffins. Some small lumps are acceptable.
05 - Sprinkle chocolate chips over batter and fold in briefly to distribute evenly throughout the mixture.
06 - Divide batter evenly among the 12 muffin cups, filling each about three-quarters full. Press additional chocolate chips onto tops if desired.
07 - Bake for 18 to 22 minutes until tops are golden and a toothpick inserted into the center comes out clean or with a few moist crumbs. Avoid overbaking.
08 - Let muffins rest in tin for 5 minutes to set. Remove carefully and transfer to a wire rack to cool completely before storing.