Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius), and line a muffin tin with paper liners. Set aside.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until well combined. Set aside.
1 1/2 cups all-purpose flour, 1 teaspoon baking powder, 1 teaspoon baking soda, 1/2 teaspoon salt
In a second large mixing bowl, combine the mashed bananas, melted butter, brown sugar, egg, and vanilla extract. Mix until everything is well incorporated.
1 1/2 cups ~4 medium or 3 large ripe bananas, mashed, 8 Tablespoons unsalted butter, 3/4 cup packed brown sugar, 1 large egg, 1 teaspoon pure vanilla extract
Add the dry ingredients to the wet ingredients, and mix until just combined. Be careful not to overmix the batter as this can make the muffins tough!
Using a rubber spatula, gently fold in the mini chocolate chips.
1 cup mini chocolate chips
Use a cookie scoop or spoon to divide the batter evenly among the muffin cups, filling each about 3/4 of the way full.
Bake for 23-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the pan for 5 minutes. Then, transfer them to a wire rack to cool completely.
Serve and enjoy!
Store at room temperature for 2-3 days or in the fridge for up to 1 week.