Preheat oven to 325. Butter a large size loaf pan, 9x5x2 and line with parchment paper leaving a generous overhand on sides. Whisk flour, cocoa powder, salt and baking powder in a medium bowl, set aside.
In electric mixer beat oil, 1/4 cup butter and 1 1/2 cups sugar until pale, 5 to 7 minutes. Add eggs one at a time, beating until blended; after last addition beat 5 minutes until volume has expanded. Add vanilla. Reduce mixer speed to low and add dry ingredients in 3 additions, alternating with buttermilk, beginning and ending with dry ingredients. Do not overmix. Scrape half the batter into prepared pan. With spatula make a canal in middle of batter, add the coconut and remaining 1 tablespoon of sugar. Add the rest of the batter gently, sprinkle a little coconut on top. Put in oven for 1 hour 15 minutes. Check at 1 hour, ovens may vary, you may need even 1 hour and 30 minutes. Remove from oven and let cake cool in pan at least 30 minutes. Enjoy