Shake with ice and serve in a punch glass. Dust with nutmeg.
To turn this into quick brandy eggnog by the glass, add a small egg and substitute heavy cream for one of the ounces of milk. I found a delicious version of this in The Flowing Bowl by Edward Spencer, called Arctic Regions and made with 4 ounces whole milk, 2 ounces sherry (medium to sweet), and 1 ounce brandy. Shake well with ice and serve over ice that's been dusted with cinnamon.