1. Preheat the oven to 350 degrees F or 175 degrees C and arrange two racks in the oven. Line two baking sheets with parchment paper. 

2. In a small bowl mix the ground flaxseeds and water together. Set aside. 

3. In a medium bowl, sift the flour, cocoa powder, brewer’s yeast, salt, and baking soda together. 

4. In another bowl or the bowl of a stand mixer, cream the sugars and coconut oil until light and fluffy. Add the vanilla and mix until incorporated. Then add the ground flaxseed and water mixture. Mix until homogenous. Add the dry ingredients and slowly mix until the dough comes together. Fold in the macadamia nuts. 

5. Divide the dough into four equal parts. Roll each quarter into a 1 inch thick log. Place two logs on each baking sheet. Bake for 25 minutes, rotating the sheets between the racks in the middle, until the top begins to crack. Cool the half baked biscotti on a wire rack. 

6. Preheat oven to 325 degrees F or 160 degrees C. 

7. Once the half biscotti logs are completely cool, cut into 1/4 inch or about 6.5 millimeters thick slices. Arrange the slices onto the baking sheets. Bake for 15-18 minutes or until firm and crisp. Remove from the oven and cool on a wire rack. Store in an airtight container at room temperature.