Gather all of your ingredients and equipment before you get started!

In a medium bowl, whisk together the flour, cream of tartar, salt, baking soda, and ½ teaspoon nutmeg. Set aside.

In a large bowl, use a handheld mixer on medium-high speed to beat the softened butter and 1 cup sugar until light and fluffy.

Beat in the egg and rum extract (if using) until fully incorporated.

Gradually add the dry ingredients, mixing on medium-low speed until just a few dry streaks remain.

Pour in the eggnog and mix until just combined.

Cover the dough and refrigerate for at least 2 hours or overnight.

In a small bowl, whisk together ¼ cup sugar, ½ teaspoon cinnamon, and ¼ teaspoon nutmeg for rolling the dough.

Use a medium cookie scoop (about 2 tablespoons) to portion the dough and roll into balls.

Roll each dough ball in the cinnamon sugar mixture until coated.

Arrange cookies on the prepared baking sheets, spacing 2 inches apart.

Bake for 8 – 10 minutes, until the cookies are puffed and edges are set.

Let the cookies cool on the baking sheet for 10 minutes before transferring to a wire rack to cool completely.