Rinse the apples, then core and cut into quarters. Juice the apples in a juicer and transfer half of the juice to a medium-sized enameled cast-iron pot.
Bring the apple juice to a boil over high heat. Reduce heat to medium and simmer, uncovered for 30 minutes. Add the rest of the juice and bring back to a boil. Gently stir with a long-handled spoon, reduce heat