Preheat the oven to 325 degrees. Line an 8x8 baking dish with parchment paper or spray with cooking spray.
In a large bowl or stand mixer, combine the buckwheat flour, coconut sugar, cacao powder, cinnamon, baking powder, baking soda, and sea salt. Stir.
In a separate medium bowl, whisk together the eggs, coconut oil, dairy-free milk, and vanilla extract. Incorporate the wet ingredients into the bowl with the flour mixture and beat until a batter is formed.
Pour batter into the baking dish. Top with goji berries, shredded coconut, and pistachios. Use a rubber spatula or wooden spoon to press the toppings gently into the batter.
Bake 22 to 25 minutes or until a toothpick comes out clean.
Allow the brownies to completely cool (about an hour) before removing from the baking dish and slicing into squares.