Preheat your oven to 350°F (175°C) and grease an 8x8 inch baking pan with butter or line it with parchment paper.

In a large mixing bowl, mash 2-3 ripe bananas until smooth. Add the melted unsalted butter and brown sugar, stirring until well combined.

Crack in one large egg and pour in a splash of vanilla extract, mixing thoroughly until fully combined.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

Gradually add the dry ingredient mixture to the wet banana mixture, stirring gently until just combined.

Fold in optional chocolate chips or nuts gently into the batter.

Pour the batter into the prepared baking pan, smoothing the top evenly.

Bake for 25-30 minutes, checking doneness with a toothpick.

Cool in the pan for 10-15 minutes, then transfer to a wire rack to cool completely.