Preheat oven to 325 degrees
Combine cocoa powder, coconut flour, and salt, and set aside
Add eyrthritol, eggs, vanilla and mix with a hand mixer. Mix until the volume of the mixture has tripled in size. This should take about 3-5 minutes on high.
In a 3rd bowl, melt together butter and bakers chocolate. This can be done using a double boiler method, or by repeatedly microwaving for 20s and mixing. If using the microwave be careful not to burn the chocolate.
Add egg mixture to the butter/chocolate mixture in 3 parts, folding in each time. Most of the erythritol will be at the bottom of the egg mixture, thats ok!
Once the wet ingredients are all combined, begin adding the dry ingredients. Add 1/3 of the dry mixture and fold into the wet. Repeat this process 3 times until all of the dry mixture is used and a homogeneous brownie batter is formed.
Pour into a greased 8x4 loaf pan.
Place into a 325 degree oven for 50-55 minutes.