Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
In a large mixing bowl, combine the mashed bananas, granulated sugar, brown sugar, and melted butter. Mix until well combined.
Stir in the beaten egg and vanilla extract until smooth.
Sprinkle the baking soda and salt over the mixture and stir to combine.
Gradually add the flour and cocoa powder, mixing until just combined. Be careful not to overmix.
Fold in the chocolate chips until evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean. If the top starts to brown too quickly, cover it loosely with aluminum foil.
Allow the bread to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.