1 oz column still aged Cuban rum½ oz blended overproof rum½ oz Bénédictine½ oz Demerara syrup (1:1)1 oz heavy cream1 whole egg
instructions :

Combine all the ingredients in a shaker and shake, without ice, until the cream and egg are emulsified. Add ice and shake again to chill. Strain into a rocks glass over fresh ice.

source :