Heat oven to 325 degrees. Score ham with diagonal lines about 1/4 inch deep to achieve a diamond pattern. Place fat side up in a shallow roasting pan lined with aluminum foil for fast clean-up. Bake 30 minutes.
Combine brown sugar, syrup, and mustard. Brush mixture on ham. Return to oven and bake another 30 minutes. Brush again with juices. Bake another 20 minutes or until 140 degrees internal temperature. Remove ham from oven and let it rest 20 minutes. Slive and serve.