Preheat oven to 375 degrees F.
In a large mixing bowl, or bowl of a standing mixer, combine the sugars, eggs, shortening, and vanilla.
Beat for 2 minutes, making sure to scrape the bowl.
In a separate bowl, gently whisk together the baking soda, baking powder, salt, nutmeg, and flour.
Add the flour mixture to the sugar mixture in 3 increments, alternating with the buttermilk.
Beat just until completely mixed together.
Cover loosely and refrigerate dough for 2 hours.
Using a 2 inch scoop, drop the dough onto a parchment covered cookie sheet. The scoops should be scant, and not over-filled.
Carefully sprinkle sugar on each cookie dough scoop.
Bake for 10 to 11 minutes. The cookies will crack on top. Test with a toothpick to make sure the middle is done.
Let cool on cookie sheet for 1 minute. Remove to a cooling rack.
Store cookies in an airtight container.