Preheat your oven to 350°F (175°C). Grease the loaf pan or line it with parchment paper for easy removal.
In a mixing bowl, mash the ripe bananas until smooth.
Stir in the melted butter until well combined.
Add the granulated sugar, beaten egg, and vanilla extract to the banana mixture, stirring until fully incorporated.
Sprinkle the baking soda and salt over the mixture and mix together.
Gradually fold in the flour and cocoa powder until just combined. Be careful not to overmix.
If desired, fold in the chocolate chips for an extra chocolatey flavor.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for about 55-60 minutes, or until a toothpick inserted into the center comes out clean.
Once done, remove the loaf from the oven and let it cool in the pan for about 10 minutes. Then transfer it to a cooling rack to cool completely.