Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a large mixing bowl, combine the mashed bananas and melted butter.
Stir in the sugar, egg, and vanilla extract until well mixed.
Add the baking soda and salt, then mix in the flour until just combined.
Gently fold in the chocolate chips.
Pour the batter into the prepared baking pan and spread it evenly.
Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean.
Allow the bars to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.
Cut into squares and serve.