2 cups Horehound leaves (packed)
1-1/4 cup water
4 cups dark brown sugar
1/4 cup light corn syrup
Wash horehound leaves and put in saucepan. Add water and bring to boil. Reduce heat and simmer for 15 minutes, mashing occasionally with fork. Remove from heat; cover and let cool (needs to stand at least 1/2 hour to infuse.
While infusion in cooling, butter a 9×13 pan.
Drain horehound leaves into measuring cup (I use a coffee filter to strain it). Be sure to squeeze all the liquid from the leaves. Make sure you have at least 1 cup of liquid. Discard leaves.
Pour liquid into a 4 qt. saucepan. Add brown sugar and syrup. Bring to a boil and cook to 300 degrees on a candy thermometer (hard crack stage).
Pour into prepared pan and let cool. Just before it sets up, score into squares with a knife to make it easier to break apart. When cool and set, break into pieces and store in airtight container.
Note: The infusion (liquid from the leaves) can be frozen to use later.