Preheat your oven to 350°F (175°C) and grease a 9x9-inch baking pan or line it with parchment paper.

Mash the ripe bananas in a large mixing bowl until smooth. Then, mix in the melted butter, brown sugar, egg, and vanilla extract until well combined.

Whisk together the baking soda, salt, and flour in a separate bowl.

Combine the dry ingredients with the wet mixture gradually and stir until just combined; avoid overmixing.

Fold in the chocolate chips and optional nuts gently.

Pour the batter into the prepared baking pan and spread it evenly.

Bake for 20–25 minutes until the edges are lightly golden and a toothpick inserted in the center comes out clean.

Cool the bars in the pan for about 10 minutes, then transfer to a wire rack to cool completely.

Slice into bars and serve.