Fill a glass with ice. Pour cold brew, chilled strong coffee, or cooled espresso over the ice.
Top with eggnog.
If making the cold foam, add ingredients to a small glass and froth.
When frothed to your liking, stop.
Make sure your glass has room for the cold foam. Mind did not. Carefully pour your cold foam on top of your latte.
Sprinkle with more nutmeg if desired. Enjoy your holiday iced or hot latte.