Preheat. Preheat oven to 350°F.
Rinse the ham. Rinse the ham under cool water and place it in the roasting pan you will be using.
Remove the skin. If your ham has skin, using a sharp knife, carefully cut underneath the skin and remove it, leaving the layer of fat underneath intact. Discard the skin.
Score the ham. Using a sharp knife, score the top and sides of the ham in a crisscross pattern about ¼ inch deep.
Spread the mustard. Using your hands or a small brush, cover the whole ham with mustard.
Prepare the pineapple mixture. In a bowl, combine the juice from the pineapple can and the juice from the marachino cherry jar with the brown sugar. Whisk until everything is well combined.
Reserve some of the mixture. Set aside 1 cup of the pineapple mixture to use for making the glaze later.
Stud with cloves. Press a whole clove into each center of the crisscross.
Add the pineapple and cherries. Using toothpicks, secure the pineapple slices and the marachino cherries around the top and sides of the ham.
Add the pineapple mixture. Pour the remaining pineapple mixture all over the ham. Cover the roasting pan tightly with aluminum foil.
Bake the ham. Bake for about 1½ to 2 hours, depending on the size of your ham or until the internal temperature reaches 140°F.
Baste ham. Remove ham from the oven in between cooking time, uncover and pour pan drippings over ham. Leave ham uncovered and continue baking until fully cooked.
Prepare the glaze. While the ham finishes baking, add the reserved cup of pineapple and marachino nectar to a small saucepan over medium-low heat.
Add the cornstarch. Whisk in the cornstarch until there are no lumps. Continue heating and stirring until the glaze starts to thicken. Turn off the heat.
Brush on the glaze. Remove the ham from the oven, raise heat to 400 degrees F. Brush the homemade glaze all over. Return the ham to the oven and bake for another 20 minutes to caramelize the top and sides.
Let the ham rest. Once the ham is done, remove it from the oven and let it rest for 15 minutes before slicing.
Remove the cloves and slice. Remove the toothpicks, whole cloves, pineapple slices, cherries and slice your ham to desired thickness. Enjoy!