- Preheat oven to 325 degrees.
- Place ham in roasting pan, cut side down, fat side up. Score ham in 1-inch wide cross-hatch pattern about ½-inch deep.
- Pour cider, brandy, and water over ham. Cover with foil tent, making sure foil does not touch ham. Cook until internal temperature reaches 135 degrees, about 3-4 hours, basting every 30 minutes. Remove from oven and remove foil.
- Raise oven temperature to 375 degrees. Combine brown sugar and mustard; slather on ham and return to oven uncovered. Cook for about 30 minutes, until golden. Remove from oven and let rest for 20 minutes before serving.