For the chocolate muffins, first heat the oven to 180 degrees. Place paper cups in the cavities of the muffin tray.
In a baking bowl, mix the baking powder, flour, baking soda and cocoa powder. Beat the egg in another large baking bowl. Add the brown sugar, oil, and buttermilk and mix well. Then gently fold in the flour mixture and fill the ramekins halfway with it, as the chocolate muffins can get very tall. Bake in the oven for 20-25 minutes.