Combine Wet Ingredients: Cream together unsalted butter (or vegan plant based butter) and brown sugar until light and creamy with a mixer or with whisk and strong muscles. Add in eggs (or ground flax seeds and water to keep vegan) and vanilla until well combined. (If using the vegan ground flax seed and water combination, allow the flax seed mixture to sit for 5 minutes. It should thicken up to the consistency of applesauce.)
Mix the Dry ingredients: In a separate bowl mix gluten-free flour blend WITH xanthan gum (or all-purpose flour if no gluten sensitivities) cornstarch, unsweetened cocoa powder, baking soda and salt.
Slowly add the dry ingredients into the wet ingredients with the mixer on low speed just until combined.
Stir In Add Ins: Using a spatula, fold in chopped macadamia nuts and chocolate chips into the cookie dough. Reserve ¼ cup of chopped macadamia nuts and chocolate chips to decorate each cookie balls before it bakes. (This is not required - but you get extra style points for pretty cookies.
Refrigerate: Cover the cookie dough and refrigerate for at least 2 hours or overnight. Refrigeration prevents the cookies from spreading!
Preheat oven to 350°F (176°C)
Form into Balls: Shape cookie dough into approximately 1.5 tablespoon balls. Place them on a lined baking tray about 3 inches apart. Stud the cookies with the remaining chocolate chips and macadamia nuts before baking. (Refrigerated dough will be quite firm - but is softens in just a few minutes once you start to working with the cookie dough.)
Bake cookies in the middle rack for 8 to10 minutes. At the 7 minute mark, pull the cookie tray out of the oven and give it one good whack on the countertop. This will confirm that the cookies are perfect thickness so they cook more evenly. Immediately, return the cookies back into the oven to finish baking.
Cookies are perfectly baked when the edges are firm and do not leave dents when you touch them with your finger. The middle and top will still be soft. Do not overbake! 9 minutes was the perfect time for our oven but each oven varies a little.
Allow the cookies to cool for about 5 minutes on the baking sheet and then carefully use a spatula and move them to a wire rack to cool. While the cookies are still hot, sprinkle on a little flaky sea salt if you like the sweet and salty combo.
Enjoy! You can freeze these cookies so you can enjoy them through the holidays, if they last that long!