Preheat the oven to 350 degrees. Line a baking sheet with parchment paper.

In a small bowl, stir together the topping: sugar, cinnamon, nutmeg, and holiday sprinkles. Set aside.

In a large bowl or stand mixer, cream the butter, brown sugar, and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Mix in the vanilla extract and eggnog flavoring.

In a separate bowl, whisk together the flour, cream of tartar, salt, and baking soda.

Add the dry ingredients to the wet ingredients and mix on low speed until a soft dough forms.

Scoop the dough into 1 tablespoon portions and roll into balls.

Roll the tops and sides of each dough ball in the cinnamon sugar topping.

Place on the baking sheet, leaving space for spreading. Bake for 10 to 12 minutes until the edges are set and the centers look slightly puffy.

Cool on the baking sheet for 5 minutes, then transfer to a cooling rack.