Preheat the Oven
Preheat your oven to 350°F (175°C) and line a muffin tin with muffin liners or lightly grease the tin.
Mash the Bananas
In a large bowl, mash the ripe bananas with a fork until smooth but slightly chunky.
Mix the Dry Ingredients
In a separate bowl, whisk together the flour, baking soda, baking powder, and salt. Set aside.
Combine Wet Ingredients
In another bowl, mix the melted butter (or oil) with the brown sugar until smooth. Add the egg and vanilla extract, stirring until fully combined. Fold in the mashed bananas.
Combine Wet and Dry Ingredients
Add the dry ingredients to the wet ingredients, mixing gently until just combined. Be careful not to overmix, as this can make the muffins dense.
Fold in the Chocolate Chips
Gently fold in the chocolate chips, distributing them evenly throughout the batter.
Fill the Muffin Tin
Spoon the muffin batter into the muffin tin, filling each cup about ¾ of the way full.
Bake
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean. The tops should be golden brown.
Cool
Allow the muffins to cool in the tin for 5 minutes before transferring them to a cooling rack to cool completely.