Pre-heat oven to 325 degrees. Grease a 9 x 9 baking pain.
In a double boiler over medium high heat (or in a heat-proof bowl sitting over a saucepan with an inch or two of water in it) melt the chocolate and shortening and stir together. Let cool and then whisk in the coconut sugar. Whisk in the eggs, one at a time, making sure they are completely incorporated. Then add vanilla.
In a separate bowl, whisk together the buckwheat, baking soda and sea salt.
Add the flour mixture to the chocolate mixture and stir until combined.
Stir in the chocolate chips or walnuts, if desired,
Smooth batter into prepared pan and bake a 325 degrees for 20-22 minutes. Do not overbake! If you use a glass or an 8x8 pan you may have to adjust the baking time a bit. Let baked brownies cool and enjoy!
These brownies keep well, wrapped tightly, for several days and up to a week or freeze well for several months.