Place chocolate and butter in a bowl. In a saucepan over high heat, bring heavy cream to boil. Remove from heat and add herbs. Return to boil then strain over chocolate and butter, pressing down on herbs to extract cream. Let mixture sit for 2 to 3 min. until the chocolate and butter have melted, then stir until ingredients are well combined and ganache is smooth. Place mixture in refrigerator for one half hour until firm. Create truffles by scooping 1 Tbsp. of ganache and forming into 1-inch balls. Roll truffles in Dutch cocoa powder to coat.
Serve at room temperature.