01 -
Whisk together flour, baking powder, nutmeg, cinnamon, and salt in a medium bowl until evenly mixed.
02 -
Beat softened butter with a stand or handheld mixer on medium-high speed for 30 to 45 seconds until creamy.
03 -
Incorporate granulated and dark brown sugars, beating for 1 to 1½ minutes until well blended and fluffy.
04 -
Reduce mixer speed to medium-low and add eggs one at a time, mixing thoroughly after each addition until no yellow streaks remain.
05 -
Mix in vanilla and rum extracts just until combined.
06 -
Alternately add the flour mixture and eggnog to the butter mixture in increments, beginning and ending with flour. Mix until just smooth. Cover and refrigerate dough for at least 1 hour.
07 -
Preheat oven to 350°F. Line two baking sheets with parchment paper.
08 -
Scoop dough with a 1½-tablespoon cookie scoop, space 2 inches apart on baking sheets. Bake for 10 to 12 minutes or until edges are golden brown. Cool cookies on sheets 2 to 3 minutes, then transfer to wire racks to cool completely.
09 -
Beat softened butter on medium speed for 45 seconds to 1 minute until creamy. Reduce mixer speed to medium-low and gradually add powdered sugar and eggnog, alternating until smooth and fully incorporated.
10 -
Fill a piping bag fitted with a star tip or a ziplock bag with frosting. Pipe onto cooled cookies with gentle pressure and lightly dust tops with ground nutmeg if desired.