Add horehound and water to a small saucepan. Bring to a boil, and simmer gently for 20 minutes. Liquid should look almost like coffee.
Let liquid cool. Strain off the liquid, squeezing all possible liquid out of the horehound. Return strained liquid to small saucepan, and discard the horehound.
Add honey to horehound liquid. Stirring very frequently, simmer gently until it reaches the "hard crack" stage - about 300 degrees on a candy thermometer. My preferred method is to drip a little drop from a spoon into a jar of ice water. When the drip turns into a very hard little ball (like a cough drop!), the mixture is ready.
Pour liquid onto a cookie sheet, or into a 13x9 pan - something with a big surface area. You want to the mixture to start cooling quickly so you can work with it!
Working from the edges, scoop up teaspoonfuls of the mixture, and roll into balls. Place on parchment-lined cookie sheet, being careful not to let cough drops touch each other.
You do have to work fairly quickly to get it all rolled before the end of it firms up too much. But there's plenty of time to enjoy the project, and enlist the help of little hands! It's FUN playing with super sticky "candy!"
When the cough drops are COMPLETELY cooled (I like to wait at least an hour), roll them up individually in squares of parchment paper. I just tear parchment paper into very rough squares, but a size about 2"x2" works nicely.
Store in an airtight container in a cool, dry location.