Frosted Eggnog Cookies

Preheat oven to 350°F (175°C). Line two or three baking sheets with parchment paper or silicone mats.
In a medium bowl, whisk together the flour, baking powder, salt, nutmeg, and cinnamon.
In a large bowl, beat the softened butter, granulated sugar, and brown sugar on medium speed until light and fluffy, about 2 to 3 minutes. Scrape down the sides as needed.
Add egg yolks one at a time, mixing well after each addition. Beat in vanilla extract, rum extract, and eggnog until smooth (mixture may look a bit curdled—this is fine).
Gradually add the dry ingredients into wet mixture, mixing on low or folding gently just until combined. Do not overmix.
Scoop heaping tablespoons of dough onto prepared baking sheets, spacing about 2 inches apart.
Bake 10–12 minutes, until edges look set and lightly golden. Let cool on trays for 5 minutes, then transfer to a wire rack to finish cooling.
For the frosting: Beat the butter until smooth. Gradually mix in powdered sugar, covering mixer with a towel to avoid mess. Add 2 tbsp eggnog and rum extract, then beat until creamy and light. Add more eggnog 1 tsp at a time as needed for spreading consistency.
Once cookies are completely cool, frost generously. Garnish each with freshly grated nutmeg. Let frosting set for 10 minutes, or enjoy immediately.