Preheat your oven to 425°F (220°C). Line a muffin pan with paper liners to make for easy clean-up later. Make sure to give your muffin cups a good space so that they have room to rise!
In a large mixing bowl, combine the mashed bananas and melted butter. Mix thoroughly until they are well combined, and the mixture is nice and smooth. You want that luscious banana flavor to shine through!
Add in the brown sugar, white sugar, egg, and vanilla extract. Whisk everything together until you achieve a creamy texture.
In a separate bowl, whisk the flour, baking powder, baking soda, and salt. This dry mixture is essential for creating the perfect rise in your muffins.
Now, slowly fold the dry ingredients into the wet ingredients. Be careful not to overmix; we want the muffins to be fluffy and light.
Stir in the sour cream and gently fold in the chocolate chips. The batter should be thick but not dry. You should see pockets of chocolate throughout!
Scoop the muffin batter into the prepared muffin liners, filling them almost to the top. Don’t be shy with the batter; you want those muffins to have a nice dome!
Sprinkle a few additional chocolate chips on top of each muffin for that extra treat. Who can resist more chocolate?
Place the muffin pan in the preheated oven and bake for 5 minutes at 425°F. Then, without opening the oven, reduce the temperature to 350°F (175°C) and bake for an additional 11 to 13 minutes. You’re looking for a light golden brown on top, and a toothpick should come out clean when inserted in the center.
Once baked, let the muffins cool in the pan for a few minutes before transferring them to a wire rack to cool completely. Enjoy these delightful little morsels!