1½ oz column still aged rum½ oz pot still unaged overproof rum¼ oz lime juice¼ oz lemon juice¼ oz rich simple syrup (2:1)2 drop vanilla extract2 oz coconut cream1½ dash Angostura bitters
instructions :

Combine the ingredients in a shaker filled with crushed ice.
Shake to chill.
Strain into glass filled with crushed ice.
Top with bitters and garnish

source :
Jonathan Buckley, South Seas Tiki Lounge (Charleston, South Carolina)