Preheat oven to 400 degrees F. Line 9 muffin cups with paper liners. If you're making jumbo size muffins, line 4 or 5 cups.
Mix the flour, baking powder, baking soda and salt together in a bowl. When well mixed, stir in the cocoa powder and evaporated cane juice (or sugar or sugar substitute). Stir in the chocolate chips.
In a mixing bowl, whisk together coconut oil and egg. When well mixed, gradually whisk in buttermilk and vanilla. Add the dry mixture to the wet mixture and stir just until blended.
Divide batter evenly among the muffin cups. It should come up almost to the top of each cup. Bake on center rack for 22 minutes or until the muffins appear set. Let cool in the muffin tin.