Warm the eggnog and milk in a small saucepan over medium-low until steaming, not boiling.
Brew the espresso while the nog mixture heats.
Whisk in vanilla, cinnamon, nutmeg, and sweetener. Froth with a whisk or frother if desired.
Divide the hot espresso between two mugs.
Pour the spiced nog over the espresso. Top with whipped cream and a light dusting of nutmeg.