Fill a cocktail shaker with ice then pour the creme de noyaux, white creme de cacao, and heavy cream into the cocktail shaker.
Cap the shaker tightly and shake vigorously until the outside of the shaker is very cold (about 15 seconds), until the mixture is well-chilled and frothy.
Strain the cocktail into a chilled coupe glass or martini glass.
Grate fresh nutmeg over the top and serve immediately.