1Combine butter and eggnog together in a saucepan over medium-low heat until heated through, about 1 minute. Pour butter mixture into a bowl and add confectioners' sugar. Beat mixture with an electric mixer until frosting is smooth, 3 to 5 minutes. Add milk if frosting is too thick, beating until desired consistency is reached.
Footnotes
Cook's Note:
The eggnog flavor is strong in this recipe, even with only using 2 tablespoons. If you like an even stronger eggnog flavor, just substitute the whole milk with more eggnog.