Make syrup as usual, getting it to 219°F and filtering as you always do, and reserve the amount you intend to infuse.
Into this set aside jar, add your extras. Let steep for about one hour – taste at the half-hour mark for flavor intensity.
Remove the ingredients, reheat syrup to at least 180°F, filter if desired to remove sugar sand, and seal as usual.
For a fun presentation, drop a vanilla bean (or cinnamon stick) in the jar before sealing.