Orange Juice Candied Yams with Apples

Name: Orange Juice Candied Yams with Apples
Ingredients: 1 tablespoon unsalted butter (softened, for smearing around the casserole dish.); 5 large sweet potatoes* (peeled and chopped into bite size chunks. (About 4-4.5 lbs).); 5 apples (peeled, cored, and sliced. I used Fuji but you can use any variety.); 1 cup light brown sugar (packed); 1 cup granulated sugar; 4 tablespoons cornstarch; 2 tablespoons orange zest ((the zest of about 2-3 large oranges)); 4 tablespoons unsalted butter; 1/2 teaspoon salt; 1 cup orange juice concentrate; 1 1/2 cups reserved apple water (reserved after you cook the apples)