Preheat your oven to 325°F / 180°C.
Generously butter a 9 x 4 loaf tin.
In a large bowl, combine mashed banana, melted coconut oil, brown sugar, eggs, and vanilla. Mix well.
In a smaller bowl, sift together baking soda, salt, flour, flour, and cocoa powder.
Add the dry mix to the wet, and stir together to just combine.
Fold the chopped chocolate through the mixture. Scrape the batter into the prepared baking tin.
In a small bowl combine coconut flakes and brown sugar. Sprinkle this mixture evenly over the batter, and then place the tin in the oven to bake.
Bake for 55-65 minutes. The loaf should be puffed and golden on top, and a toothpick or cake tester inserted should come out clean - however, if you hit a chunk of melted chocolate that might fool you. Check a few spots to be safe.
Let the loaf cool in the tin for 10 minutes, and then turn out onto a wire rack.
Enjoy warm, or at room temperature.