1½ oz absinthe½ oz lemon juice¾ oz falernum6 mint leaf½ oz Angostura bitters
instructions :

Use a muddler to gently crush the mint leaves with the falernum in the bottom of a Collins glass.
Add the remaining ingredients and fill halfway with crushed ice; use a tsp to swizzle the mixture for several seconds.
Pack the glass with additional crushed ice to fill, and layer ½ oz of Angostura bitters on top of the surface.
Garnish and serve with a straw.

source :