The syrup is made from juice that has been boiled in order to preserve it and maintain the distinctive features of the raw material intact. Three different sugar cane varieties are used to produce the syrup, which then undergoes fermentation similar to the tradition of Grand Arôme, where the residual material left in the pot after distillation (often called dunder, backset or stillage) is added back to the fermenting wash.

This addition allows much more intense aromas to develop during fermentation, which are then also revealed in the finished spirit. Le Rocher is characteristic of a heavy richness and an intriguing smokey sweetness. Le Rocher is represented by a painting found on the walls of the famous Hotel Florita in Jacmel, Haiti.