Shake until the shaker feels very cold in your hand.
Strain into a chilled coupe glass.
Garnish with chocolate shavings and/or fresh mint.
Notes
You can substitute the heavy whipping cream or half and half or a non-dairy creamer if needed. This will result in a slightly less frothy cocktail, but it will still be delicious. To make a frozen grasshopper cocktail, substitute the heavy cream for 1 cup vanilla ice cream and blend in a blender instead of a cocktail shaker.