Line a large plate, platter, or cookie sheet with wax paper. Set aside for now. This will be used for chilling the balls of dough.
Line another baking sheet with parchment paper (for baking) and set aside for now.
Mix together dry ingredients (flour, baking soda, baking powder, nutmeg, salt and cream of tartar). Set aside.
Start mixing "wet" ingredients: In a separate bowl, cream room temperature butter, vanilla extract, and rum extract together. Add sugars (brown and granulated) and mix until fluffy.
Add egg and eggnog and mix well.
Stir in combined dry ingredients, half of the mixture at a time, stirring until JUST mixed each time.
Use a small cookie scoop or spoon to scoop out approximately 1 inch balls, and use your hands to gently roll them into a ball. Place onto prepared plate (with the wax paper).
Place cookie sheet in the refrigerator to chill for at least 1 hour.
When done chilling, preheat oven to 350 F degrees.
Roll each ball into sugar topping mixture and place back onto wax paper lined plate.
Place cookie dough balls onto prepared baking sheet, leaving 2 inches in between for optimal baking, slightly flatten each ball, and bake 8-10 minutes.
Let cool on baking sheet for 5-7 minutes before transferring to wire cooling rack.
You will have to bake the cookies in batches, so be sure to put the cookie dough balls back into the refrigerator while the other ones are baking.