-Preheat your oven to 325º.
-Cut the ham lengthwise to allow the center to cook more thoroughly, and turn one half around so the centers aren't touching.
-Add about 1/3 c. water, and cover loosely with aluminum foil. This prevents the top from getting burnt-looking.-Put the lid of your casserole dish on, and into the oven it goes!
If you don't have a lid, just cover tightly with foil.
I like to cook mine for about 1 hour, 15 minutes, then turn the oven OFF for about 3 hours. This is the best cook time in my opinion, and I've even done it when headed to church on Sunday morning, and reheated the ham along with any casseroles I have prepared.
If you don't have that much time, I would cook the ham about 2 hours, and leave the oven OFF for an hour.
You can vary back and forth between the cook and OFF times, and even cook it for 2½ hours straight.
But the longer it gets to slow-cook while the oven is turned OFF, the better.
If you don't care for it being so juicy, right after re-heating, drain some of the liquid before it has time to soak back into the ham as the ham cools.