1½ oz blended aged rum¾ oz lime juice½ oz honey½ oz ginger juice5-7 mint leaves1 top soda water½ oz black blended rum, to float
instructions :

Muddle the mint in a shaker tin, then add the remaining ingredients (minus the blackstrap rum), plus ice.

Shake to chill, double strain into a Collins glass filled with fresh ice.

Top with soda, float with the blackstrap, then garnish.

source :
imbibemagazine.com