2 cl green crème de menthe (mint liqueur)
2 cl white crème de cacao (cocoa liqueur)
2 cl cream

Fill a cocktail shaker with ice up to ¾. Pour the liqueurs and the cream over the ice, shake and strain in a chilled cocktail glass. Serve as an after dinner cocktail.
Serves 1.

Note: in order to give this cocktail its appropriate pale green colour, it is important to use green, not white, mint liqueur and white, not brown, cocoa liqueur. Using brown cocoa liqueur mixed with green mint liqueur would give the drink a dull, unattractive colour  —  which, of course, does not affect the taste (unless you happen to be a hopeless aesthetic :-)

Recipe source: traditional recipe.