1 oz column still aged rum1 oz dry curaçao¾ oz lemon juice¼ oz rich simple syrup (2:1)¾ oz Fernet-Branca, to float5-10 mint leaves
instructions :

Place 5-10 mint leaves at base of glass then add the remaining ingredients, except Fernet-Branca. Add crushed ice and swizzle until glass is frosted, approximately 20 seconds.

Add straw, then slowly pour Fernet over the top of the ice. Top with crushed ice and garnish.

source :
imbibemagazine.com