Preheat oven to 350.
Line a muffin tin with liners, or if you don't have any, make sure to grease the pan well.
In a medium size bowl, prepare the muffin mix according to package instructions.
Next, pour half of the batter into a small bowl, and add the cacao powder. Mix together well so there are no clumps.
Fold in about half of the chocolate chips into the banana bread batter.
Now, the fun part.
Add a spoonful of banana bread muffin batter to each muffin cup. Then add a spoonful of the chocolate banana bread batter, and repeat until no batter remains.
Sprinkle remaining chocolate chips on top, and bake for 25 minutes.