In a bowl, whisk together the flour, baking powder, cinnamon, and nutmeg.

In another bowl, cream butter and sugar together.

Add egg yolks, vanilla and eggnog and beat until smooth.

Gradually add the dry ingredients into the wet ingredients and stir until combined.

Place in the refrigerator and chill dough for at least 30 minutes.

Preheat oven to 350 degrees Fahrenheit and line a baking sheet with parchment paper.

Place teaspoon sized balls of dough onto the prepared baking sheet.

Bake for 18 minutes or until bottoms are lightly browned.

Place cookies on a wire rack to cool.

To make the icing, mix the powdered sugar, butter and eggnog until blended.

Spread icing onto the cooled cookies and sprinkle with nutmeg.