In a pitcher, stir the first four ingredients together until the sugar and espresso are dissolved. Stir in the eggnog. Cover and refrigerate. (Can be prepared 1 day ahead)
MAKE THE TOPPING:
In a medium bowl, use an electric mixer to beat the cream, powdered sugar and vanilla together to soft peaks.
Pour the eggnog into punch cups. Top with a dollop of cream, sprinkle with nutmeg and serve.