Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a mixing bowl, mash the ripe bananas until smooth.
Add melted butter to the mashed bananas and mix well.
Stir in the baking soda and salt.
Add the sugar, beaten egg, and vanilla extract; mix until combined.
Gradually add the flour, mixing until just incorporated.
Fold in the chocolate chips, being careful not to overmix.
Evenly distribute the batter into the prepared muffin tin.
Bake in the preheated oven for 20-25 minutes or until a toothpick comes out clean.
Allow muffins to cool in the pan for 5 minutes before transferring to a wire rack.