Preheat your oven to 350°F (175°C). Gather your mixing bowls and your 8x8 inch baking dish.

In a large mixing bowl, whisk together the melted butter and brown sugar until smooth and glossy.

Add the mashed ripe bananas, large egg, and vanilla extract to the bowl. Mix well until integrated.

Sift in the whole wheat flour, baking soda, and salt. Gently stir until just combined.

If adding chocolate chips, gently fold them into the batter.

Grease your baking dish and pour in the batter, smoothing the top with a spatula.

Bake for 30-34 minutes, or until a toothpick inserted comes out clean.

Cool in the pan for about 5 minutes before slicing into squares.