Using a spoon, scrape up about half a teaspoon of the syrup and nibs. Then, placing some softened butter on your hands, roll into little balls. Add the individual balls to each bittersweet lined truffle molds. Top with extra dark chocolate to seal the truffle. Tap the mould on the countertop to remove any air bubbles and help the chocolate fill around the caramelized cacao nib balls. Place in the refrigerator and let set until the chocolate is fully hardened, 30 – 40 minutes.