Preheat oven to 350 ° F (177 ° C). Line a loaf pan (8.5 x 4.5) with parchment paper or lightly grease. (9X5 will work too).
Combine the ground flax and water in a small bowl. Set aside for 10 minutes. It will thicken and gel up.
In a medium mixing bowl, add the flour, cocoa, baking soda, baking powder, cinnamon, and salt. Whisk to combine and set aside.
In a large mixing bowl, mash up the bananas using a fork or potato masher. Now add the oil, brown sugar, vanilla, and flax eggs. Whisk well to combine.
Add the dry ingredients into the wet and fold with a spatula until just combined. Don't overwork the batter. The batter should be very thick. Gently fold in the chocolate chips.
Pour mixture into loaf pan, then gently spread it out evenly with a spatula. Sprinkle the top with chocolate chips. Place on the center rack in your oven. Bake for 55-65 minutes or until a toothpick comes out clean (check in 3 places). Small crumbs are ok, just not wet batter. Don't confuse melted chocolate for wet batter.
Remove from oven and let the loaf cool for 10-15 minutes before transferring it to a cooling rack. Let the loaf completely cool before cutting. Enjoy!