Preheat the oven to 350°F (175°C) and line a muffin pan with paper liners.
In a mixing bowl, mash the ripe bananas with a fork.
Stir the melted butter into the mashed bananas.
Mix in the baking soda and salt.
Add the sugar, beaten egg, and vanilla extract, and mix well.
Stir in the flour until just incorporated. Add chocolate chips & mix well.
Divide the batter evenly among the muffin cups.
Bake in the preheated oven for about 20 minutes or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for a few minutes before transferring to a wire rack to cool completely