Preheat oven to 350 degrees and grease a 5.75-inch x 3-inch bread pan with coconut oil (you may use a larger pan, but the bread will come out thinner).
Make your flax egg: Combine the ground flax seeds with the 2.5 tablespoons of water, stir thoroughly, and allow to sit for 5 to 10 minutes.
Combine all of the dry ingredients in a medium bowl (oat flour, almond flour, cocoa powder, baking powder, baking soda, and salt). Stir or whisk until evenly combined. Add in the rest of the wet ingredients along with your flax egg and stir until well combined.
Stir in chocolate chips. Add batter to prepared pan and top with desired amount of chocolate chips.
Bake in preheated oven for 40-45 minutes (less time if using a larger pan) or until a toothpick comes out clean.
Allow to cool in pan for 15 minutes before removing from pan. Enjoy!