Cook diced apple and juice in a Dutch oven over medium heat 30 minutes or until apple is tender. Stir until apple is mashed. Stir in sugar and cinnamon. Pour apple mixture into a lightly greased 11- x 7-inch baking dish.
Bake at 275° for 4 1/2 hours, stirring every hour, or until spreading consistency. Cover and chill.
For Spiced Oven Apple Butter: Increase cinnamon to 2 teaspoons and add 1/2 teaspoon ground cloves and 1/4 teaspoon ground allspice.