Preheat oven to 325° F. Place apples and onions in the bottom of roasting pan. Season with salt and pepper to taste, 2 tablespoons brown sugar and 1 tablespoon corn starch--toss to coat evenly. Scatter butter cubes evenly over top. Place ham on top of apple and onion mixture and bake for 1 hour. Stir apples and onions and continue baking for about 30 minutes or until ham has about 15 minutes remaining to bake.

To make glaze: In a medium saucepan, combine apple cider and Balsamic vinegar and bring to a boil. Cook until liquid has reduced by about half. Turn off heat, add 2 tablespoons brown sugar and 1 teaspoon salt and whisk to dissolve. In a small bowl, whisk together 2 tablespoons of cold water with 2 tablespoons corn starch. Bring sauce to a boil again and add corn starch mixture, whisking constantly until sauce has thickened and coats the back of a spoon. Remove from heat.

When ham has 10-15 minutes remaining to bake, remove from oven and adjust over temperature to 375°F. Apply glaze evenly over entire ham and drizzle over apple and onion mixture. Return the ham to the oven until ham is heated through and glaze is beginning to caramelize.

Serve each slice of ham with the glazed apples and onions. Enjoy!