Clean and polish the bar moulds. Finely slice half of the rosemary and place on a baking tray (sheet). Preheat the oven to the lowest setting, about 110°C (200°F/Gas ¼). Leave the oven door ajar and dry the rosemary in the oven for 1 hour or until the leaves have dried. Set aside until needed.
To make the herb infusion, heat the cocoa butter in a saucepan until