Preheat the oven 325 degrees F. Place the ham in a roasting pan and bake 90 minutes, or until well heated through. When the ham is 20 minutes from being done, place the remaining ingredients, except cornstarch mixture, in a medium pot and bring to a gentle simmer. Simmer 5 minutes, until the pineapple is just tender. Stir in the cornstarch mixture. Return to a simmer, and simmer until the sauce thickens, about 1 minute. Serve the sauce with the ham.
Note: Spiral-cut hams are fully cooked hams that are presliced, which makes them easy to serve. The pineapple was cut into 1/2" cubes. The sauce yields about 12, 1/4-cup servings. Expand the recipe if you think you need more sauce than that.