Preheat the oven to 350 degrees F. Grease an 8 1/2 x 4 1/2-inch loaf pan. Line with a strip of parchment if desired and dust with cocoa powder.
Thoroughly whisk together the coconut flour and baking powder.
In a large, microwave-safe bowl, melt the butter with the cocoa, stirring until well blended.
Whisk the sugar, salt, vanilla, and eggs into the butter-cocoa mixture. Add the coconut flour and baking powder, whisking until smooth.
Pour the batter into the prepared pan and let it rest for exactly 10 minutes.
Bake until set, and a cake tester inserted into the middle comes out clean. Mine took exactly 35 minutes.
Let the cake in the pan for 30 minutes before turning it out onto a rack to cool completely. Let cake cool completely before slicing. Note: I let mine cool completely in the pan and didn't have any issues.