Place a rack in the upper third of the oven and preheat oven to 325°F.
Grease a 9×13-inch baking pan with coconut oil. Line the pan with foil and grease the foil. This will make brownie removal much easier.
Whisk together cocoa, coconut flour, baking soda and salt, then set aside.
Place coconut oil and chopped chocolate in a medium sized heat proof bowl. Place the bowl over a pot of barely simmering water, being sure that the bottom of the bowl does not touch the boiling water. Stir until chocolate and coconut oil are completely melted. Use pot holders to remove the bowl from over the boiling water. Let mixture sit for a few minutes.
Puree the sweet potato in a food processor until very smooth, making sure there are no lumpy bits.
In a medium sized bowl, whisk together honey, eggs and vanilla extract. Whisk until pale and thick. Pour the chocolate mixture into the egg mixture. Whisk until completely incorporated. Add the sweet potato and mix well. Add the cocoa mixture all at once and whisk to incorporate.
Pour into the prepared pan and bake for about 35 to 40 minutes, or until a skewer inserted in the center comes out clean.
Let cool and cut into 20 squares. If you’re like me, you will prefer brownies cold. If desired, dust the brownies with coconut flour or a little sea salt.