Preheat your oven to 350°F (175°C). Grease a loaf pan.
In a mixing bowl, mash the ripe bananas with a fork until smooth.
Stir the melted butter into the mashed bananas.
Mix in the sugar, beaten egg, and vanilla extract.
Sprinkle the baking soda and salt over the mixture and mix in.
Add the flour and cocoa powder, mix until just incorporated.
Fold in the chocolate chips.
Pour the batter into the prepared loaf pan.
Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.