Get organized and prepared. Allow butter, eggs and measured eggnog for the dough to sit out on the counter for an hour before mixing. This will allow them to come to room temperature. Measure out all ingredients ahead of time to help mixing go faster. 

In a medium bowl, combine flour, baking powder, baking soda, cream of tartar and nutmeg. Set aside.

In the bowl of an electric mixer, cream the butter and sugars until light and fluffy. Add the eggs one at a time, mixing after each addition.

Add the eggnog and vanilla extract and continue to mix until all combined.

Gradually add in the flour while mixing on low speed. Mix until just combined.

Cover bowl with plastic wrap and chill for one hour.

When ready to bake, preheat oven to 350°F. 

In a small bowl combine ingredients for Sugar Topping.

Round dough into 2 inch balls and roll in Sugar Topping, coating all sides.

Put dough balls onto a baking sheet lined with a silicone mat or parchment paper. Slightly flatten out dough balls with fingers.

Bake for 9-12 minutes or until edges of cookies are slightly golden.

Allow cookies to cool on the baking sheet for 10 minutes before transferring to a cooling rack.

When cookies have completely cooled, prepare to glaze.

In a medium bowl, combine all the ingredients for the glaze with a wire whisk. The glaze should be on the thick side, so adjust the powdered sugar and eggnog to get that thick consistency. 

Place the parchment under the cooling rack to catch the excess glaze. Over the bowl of glaze and with a large spoon, get a steady stream of glaze running. Drizzle the glaze over cookies in a back and forth motion. Top with sprinkles while glaze is still wet. 

The glaze should set up in about 10 minutes, making it easier to stack these cookies or bag in a cellophane gift bag.