Prepare the Dough:

1. Mix the dry ingredients:
   • In a medium bowl, whisk together the flour, baking powder, cinnamon, nutmeg, and salt. Set aside.
2. Cream the butter and sugar:
   • In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 2-3 minutes.
3. Add wet ingredients:
   • Mix in the egg, eggnog, and vanilla extract until fully combined.
4. Combine wet and dry:
   • Gradually add the dry ingredients to the wet mixture, mixing until just combined. Do not overmix.
5. Chill the dough:
   • Cover the dough and refrigerate for at least 30 minutes to make it easier to handle.

Shape and Bake:

6. Preheat the oven:
   • Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
7. Shape the cookies:
   • Scoop tablespoon-sized portions of dough and roll into balls. Place the balls 2 inches apart on the prepared baking sheets.
8. Bake:
   • Bake for 10-12 minutes, or until the edges are set and the cookies are lightly golden. Do not overbake.
9. Cool:
   • Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

Glaze the Cookies (Optional):

10. Make the glaze:
    • In a small bowl, whisk together the powdered sugar and eggnog until smooth and slightly thick.
11. Decorate:
    • Drizzle or spread the glaze over the cooled cookies and sprinkle with a pinch of nutmeg for garnish.