Preheat oven to 350°. In a medium bowl whisk together flour, baking powder, cinnamon, and nutmeg. Set aside.

In a large mixing bowl, cream butter and sugar together. Add egg yolks and vanilla to the mixture and beat until smooth. Finally, add eggnog and mix on medium speed until smooth and creamy.

Slowly add flour mixture into the eggnog mixture and stir until combined. Chill dough for 20 minutes.

Line a baking sheet with parchment paper and use a cookie scoop or drop spoonfuls of dough onto the cookie sheet. Bake for 18-22 minutes or until bottoms are lightly browned. Do not over cook. Remove cookies from pan and allow to cool on a cooling rack.

For icing, whisk powdered sugar and eggnog together. Add more sugar or eggnog, depending on the consistency you prefer.

Drizzle icing on cooled cookies and sprinkle with nutmeg. Store in a air tight container in the refrigerator.