To make the flax egg, in a small bowl combine the Ground Flaxseed (2 tablespoon) and Water (6 tablespoon). Stir, and let sit for 5 minutes before using in baked goods.
To a medium-sized mixing bowl, combine the Unsweetened Cocoa Powder (1/3 cup), Cacao Powder (1/4 cup), Granulated Sugar (3/4 cup), Brown Sugar (1/4 cup), and Olive Oil (1/4 cup). Whisk or stir till combined.
Add in the flax egg mixture and stir till combined. Once combined, add in the Vanilla Extract (1 tablespoon).
Into another medium-sized mixing bowl, combine the All-Purpose Flour (1 cup), Baking Powder (1 1/3 teaspoon), and Sea Salt (1/2 teaspoon). Stir till combined.
Add the dry ingredients to the wet ingredients bowl and stir just till well combined. Cover with a cloth, wax paper, or cling film and place in the fridge for at least 3 hours but can be left overnight
Preheat the oven to 350 degrees F (180 degrees C) and line two large baking sheets with parchment paper and set aside.
Now, roll the dough into around 1 tablespoon balls and toss them into Powdered Confectioners Sugar (3 tablespoon). Coat them well and begin placing each ball on the pre-lined baking sheets. You should be able to fit 8 cookies per sheet.
Bake for 10 minutes and cool on the baking sheet for 5 minutes before transferring them to a cooling rack.