The best way to cook ham is to bake it. Preheat your oven to 325ºF and spread a layer of mustard over the ham. Place the ham in a roasting pan, fat side up, and cover with aluminum foil. Bake for 18 minutes per pound and then remove the foil and brush more mustard onto the top. Return the ham to the oven and bake uncovered for an additional 15 minutes. Let the cooked ham rest for 10 minutes before slicing, and serve with your favorite sides.