Traditional milk punches combine milk with rum and/or brandy, citrus juice, sugar and spices. Adding club soda to this cocktail "gives it a nice puffed-up texture," says bartender Wayne Collins. It's terrific as an after-dinner drink.
Fill a cocktail shaker with ice. Add all of the remaining ingredients except the club soda and garnishes; shake well. Strain into an ice-filled highball glass; stir in the soda. Garnish with cocoa and nutmeg.