In a bowl, mix together the flour, baking powder, salt, cinnamon, and nutmeg. Set it aside for a moment.
In your mixing bowl, beat together the egg, sugar, and oil.
Add in half of the flour mixture, stirring until combined.
Add in the buttermilk, stir to combine.
Add in the remaining flour mixture, stirring until it is just combined. Scrape the bowl with a rubber spatula to ensure that all the flour is mixed in.
Fold in the chocolate chips.
Scoop the batter into a prepared muffin tin. (Cups should be lined with muffin papers or sprayed with baking spray.)
Sprinkle each muffin with a little of the demerera sugar.
Bake the muffins for 5 minutes, then reduce the heat to 375 degrees and continue baking for 13-14 minutes, or until the muffins test done with a toothpick in the center.