In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with an electric mixer, beat your butter at a medium speed, and then slowly incorporate your powdered sugar, eggnog, vanilla, and freshly grated nutmeg. Be sure to scrape down the sides of the bowl part way through.

Whip until smooth and fluffy.

Pipe onto your vanilla cupcakes, cookies, or cakes and enjoy. Store any unused eggnog frosting in an airtight container in the refrigerator.