Preheat oven to 350 degrees. Lightly coat a loaf pan with cooking spray.

Combine the ground flaxseed and water in a small bowl. Set aside.

In a mixing bowl, whisk together the mashed banana, almond butter, vanilla, brown sugar and cane sugar. Whisk in the flaxseed mixture.

Add in the whole wheat flour, cocoa powder, salt and baking powder. Stir with a wooden spoon just until combined. Mix in the chopped chocolate chunks.

Pour the batter into the loaf pan, and bake for 40 minutes, or until a toothpick comes out of the center of the bread clean.

Allow to slightly cool before cutting into 8-12 slices.