Begin by preheating your oven to 350°F (175°C). Take an 8x8 inch baking pan and line it carefully with parchment paper, making sure to leave some overhang on the sides for easy removal later.
To make the quinoa flour, start by toasting the raw quinoa in a dry skillet over medium heat for about 5 minutes, stirring frequently until it becomes fragrant and slightly golden. Allow it to cool completely to room temperature, then transfer it to a high-speed blender and process until it reaches a fine, flour-like consistency.
For the flax eggs, combine 2 tablespoons of ground flaxseed with 6 tablespoons of water in a small bowl. Stir well and let the mixture sit for 10 minutes until it becomes thick and gel-like in consistency.
In a large mixing bowl, thoroughly whisk together your homemade quinoa flour, cocoa powder, baking powder, and salt until well combined and free of any lumps.
In a separate large bowl, combine the prepared flax eggs, coconut sugar, maple syrup, sweet potato puree, melted coconut oil and vanilla extract. Whisk these wet ingredients together until they're smooth and well incorporated.
Gradually add the wet ingredients to the dry ingredients, stirring until you have a uniform batter. Be careful not to overmix. Gently fold in the chocolate chips until they're evenly distributed throughout the batter.
Pour the brownie batter into your prepared baking pan, using a spatula to smooth the top into an even layer. Sprinkle a light dusting of sea salt over the surface and add some extra chocolate chips.
Place the pan in the preheated oven and bake for 25-30 minutes. To test for doneness, insert a toothpick into the center - it should come out with a few moist crumbs, but not wet batter.
Once baked, remove from the oven and allow the brownies to cool completely in the pan before attempting to cut them. This cooling period is crucial for achieving clean cuts and the perfect fudgy texture. Once cooled, lift the brownies out using the parchment paper and cut into equal squares.