Preheat oven to 350 degrees F. Line baking sheet with parchment paper or silpat. Set aside.
In a medium bowl, add flour, baking powder, cinnamon and nutmeg. Stir to combine.
In a stand mixer or hand mixer, cream together the butter and sugar. Add eggs and vanilla extract. Mix until smooth.
Add eggnog and mix again until smooth and creamy.
Slowly add the flour mixture to the mixing bowl while on a low speed. Stir until just combined.
Using a cookie scoop or tablespoon spoon, spoon dough onto baking sheet. Bake cookies for 14-16 minutes; until the bottoms and edges are lightly browned.
Remove cookies from baking sheet and place on a wire rack. Allow to cool completely before applying glaze.
For glaze: place ingredients in a large measuring cup or glass bowl. Mix until creamy.
Then drizzle glaze onto cooled cookies. Let them sit for about 15 minutes so the glaze has a chance to harden.
Serve & Enjoy!