Remove the chocolate bar from the fridge and remove from the tray. Cut into six 10 × 2.5 cm (4 × 1 inch) bars. Place the chocolate and cocoa butter in a double boiler over simmering water and stir until melted and smooth. While warm, fill an airbrush (see Note) with the chocolate mixture and spray the chocolate all over the bars to coat evenly. Refrigerate for 15 minutes or until set.