Preheat the oven to 350 degrees F. Line a 9X9 baking pan with parchment paper and set aside.
In a small bowl, whisk together the flaxseed meal and water. Set aside while you prepare the remaining ingredients.
In a large mixing bowl, whisk together the flours, quinoa, cacao powder, arrowroot, salt, baking soda and espresso powder. Set bowl aside.
In a double boiler, add chocolate chips and coconut oil. Heat until chocolate has melted and is smooth. Remove from heat and allow to cool for 2 minutes. Once cooled, whisk in the avocado, milk, vanilla and flax egg.
Add coconut sugar to a high powdered blender and blend on high until powdery. Add sugar to the chocolate mixture and stir to combine.
Pour chocolate into dry ingredients. Stir together until a thick dough forms. The dough will be thick, so don't be tempted to add more liquid.
Transfer dough to the prepared pan and press into the pan with wet hands. Smooth the top as best as you can.
Bake on the center rack for 26 - 28 minutes. Remove and sprinkle with salt. Allow to cool for at least 1 hour in the pan before transferring to a wire rack and cooling completely. DO NOT slice the brownies before they are totally cooled down or they will be crumbly.
Store in an airtight container for up to three days.