These Soft Eggnog Cookies are covered with an Eggnog frosting.
In a large bowl, cream butter and brown sugar until light and fluffy. Beat in egg yolks, eggnog and rum extract. Gradually mix in the flour. Chill for two hours.
Preheat oven to 325°. Line baking sheets with parchment paper. Shape into 1.5 inch balls and bake for 10-12 minutes or until bottoms are golden brown (tops won't brown much). Cool completely.
For the Frosting: Beat In a large bowl, beat the first five frosting ingredients until blended; Mix in additional eggnog to reach desired consistency. Frost cookies and sprinkle with nutmeg if desired. Store in airtight containers.
The cookies will not flatten much. If you prefer a flatter cookie, flatten slightly with hand before baking.
Half a recipe of frosting is almost enough but if you want a lot of frosting make a regular batch.
Source: Taste of home. Reduced rum extract in the frosting.