It can be difficult to find a cooked ham with the bone in but it is worth the effort. The better grocery stores will order one for you.
1 Ham, bone in, fully cooked, 12-14 pounds
Place ham fat side up on a rack in a shallow pan. Bake uncovered in slow oven at 325 degrees for about 10 minutes per lb. for an already cooked ham. Take ham out of the oven ½ hour before time is up to apply the glaze.
Tangy Mustard Glaze
1 cup brown sugar
1 teaspoon dry mustard
2-3 teaspoons ham drippings
Mix ingredients together.
Score the ham diagonally creating a diamond pattern with cuts about ¼ inch deep. Spread the glaze on the ham and continue baking for about another 30 minutes.
The internal temperature should be about 130 degrees.