Preheat oven to 300 degrees. Line cookies sheets with parchment paper.
Combine the flour, baking powder, cinnamon, nutmeg together in a small bowl.
Using an electric mixer cream the sugar and butter together in a large bowl. Add the eggnog, vanilla, and egg yolks beating at medium speed until smooth.
Gradually add the dry ingredients to the wet ingredients. Beat at low speed just until blended.
Using a small ice cream scoop measure the dough out and drop them by teaspoons onto the prepared cookie sheets.
Leave 1 inch between each cookie.
Sprinkle lightly with additional nutmeg.
Bake at 350 degrees for 23-25 minutes. (Or until bottoms turn light brown.)
Allow the cookies to cool slightly before transferring to a wire rack.
Leave the cookies on a wire rack to cool completely.