Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan or line it with parchment paper.

In a large mixing bowl, combine the 3 ripe, mashed bananas with ½ cup of melted unsalted butter and stir until creamy.

Sprinkle in 1 cup of packed brown sugar and ½ cup of granulated sugar into the banana mixture, mixing until smooth.

Add 2 large eggs one at a time, stirring well after each, followed by 1 teaspoon of pure vanilla extract.

In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of baking soda, and ½ teaspoon of salt.

Gradually fold the dry mixture into the wet ingredients until just combined, avoiding overmixing.

Fold in 1 cup of semi-sweet chocolate chips and ½ cup of chopped walnuts or pecans, if desired.

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

Bake for 20-25 minutes, until a toothpick inserted comes out clean or with a few crumbs.

Allow to cool for about 10 minutes before transferring to a wire rack to cool completely.

Once cooled, cut into squares and serve.