Preheat your oven to 350°F (175°C). Grease the loaf pan or line it with parchment paper.
In a large mixing bowl, mash the ripe bananas with a fork until smooth.
Add in the melted butter, sugar, brown sugar, eggs, and vanilla extract. Mix until well combined.
In a medium mixing bowl, whisk together the flour, cocoa powder, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Be careful not to overmix.
Fold in the chocolate chips if using.
Pour the batter into the prepared loaf pan and spread it evenly.
Bake in the preheated oven for about 60 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove from the oven and let it cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.