Get out a large 6-8 quart Dutch oven or pot, a 1 cup dry measuring cup and a flat bladed table knife. Set aside.
Bring boiling-water canner, half full with water, to simmer. Wash jars and screw bands in hot soapy water; rinse with warm water. Pour boiling water over flat lids in saucepan off the heat. Let stand in hot water until ready to use. Drain jars well before filling.
Pit and finely chop 2 pounds of the cherries. Core and finely chop the unpeeled apple. I like to use my mini food processor to chop both the apple and the cherries. I just pulse it on and off until everything is finely chopped (NOT pureed).
Place the chopped apple in a 1-cup dry measuring cup. You should have around ¾-1 cup. If it’s not quite a cup, fill the rest with cherries, leveling off the fruit at the top with a knife. Transfer the mixture to the pot then add 3 more cups (leveled off) of finely chopped cherries.
Add the pectin and balsamic vinegar to the pot and stir well to combine. Bring the mixture to a full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring frequently with a sturdy spatula and scraping down the sides of the pot.
Stir in sugar, spices and butter. Return to a full rolling boil and boil exactly 1 minute, stirring constantly and scraping down the sides of the pot. Adjust the heat down a bit if the boiling mixture gets too close to the top of the pot.
Remove from the heat and skim off any foam with metal spoon. Ladle immediately into prepared jars, filling to within ¼ inch of the tops. Wipe jar rims and threads. Cover with two-piece lids. Screw bands tightly.
Place jars on an elevated rack in canner. Lower rack into canner. (Water must cover jars by 1 to 2 inches. Add boiling water, if necessary.) Cover; bring water to gentle boil. Process 10 min. Remove jars and place upright on a towel to cool completely. After jars cool, check seals by pressing middles of lids with finger. (If lids spring back, lids are not sealed and refrigeration is necessary.)