1. Combine the first 6 ingredients in a small bowl. Score outside of ham in a diamond pattern; rub with spice mixture. Cover and chill overnight.
2. Remove the ham from refrigerator; let stand at room temperature 1 hour.
3. Preheat oven to 425°.
4. Arrange ham, fat side up, on rack of a roasting pan coated with cooking spray, and place rack in pan. Bake at 425° for 30 minutes. Reduce temperature to 350° (do not remove ham from oven); bake at 350° for 1 1/2 hours.
5. Combine maple syrup, Dijon mustard, and butter. Turn ham, fat side down. Bake an additional 40 minutes, basting with syrup mixture every 20 minutes. Turn ham again. Baste with the remaining syrup mixture, and bake an additional 35 minutes or until a thermometer inserted close to bone registers 145°. Let stand for 20 minutes; remove excess fat, and slice.