Preheat oven to 350 degrees. Line a cookie sheet with parchment paper.
In a large bowl, whisk the flour, baking soda, baking powder, nutmeg, cinnamon, and salt. Set aside.
2 1/4 cup all purpose flour, 1/2 teaspoon baking soda, 1/2 teaspoon baking powder, 1 teaspoon nutmeg, 3/4 teaspoon cinnamon, 1/4 teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl using an electric hand held mixer cream together the sugars and butter until light and fluffy.
3/4 cup granulated sugar, 1/4 cup light brown sugar, 3/4 cup unsalted butter
Add in the egg and vanilla extract; mix until combined.
1 large egg, 1 1/2 teaspoon vanilla extract
Pour half of the flour mixture into the wet mixture and mix just until combined. Add the eggnog; mix until combined and then mix in the remaining flour mixture. Continue mixing until a soft dough has formed. 1/2 cup eggnog
Using a medium cookie scoop, yielding 2 tablespoons, drop balls of dough on cookie sheet 2 inches apart.
Lightly spray the bottom of a glass with non-stick cooking spray and use the glass to slightly flatten the balls of cookie dough. (push the dough down to about half of what it was in ball form, about ½ inch thick).
Bake for 9-11 minutes, just until the tops are no longer wet and the edges have started to brown.
Remove from the oven and allow to cool for 2-3 minutes while on the cookie sheet. Move the cookies to a wire rack to finish cooling completely. Glaze the cookies once fully cooled. To make the glaze, whisk the powdered sugar and eggnog until lumps have disappeared.
1 cup powdered sugar, 2-3 tablespoons eggnog
Drizzle the glaze over the cooled cookies and allow to sit until the glaze has set. The glaze will begin to set in about 15 minutes and cookies can be stacked after 1 hour.