In medium mixing bowl, combine KELLOGG'S ALL-BRAN cereal, flour and brown sugar. Using pastry blender, cut in margarine until mixture resembles coarse crumbs. Set aside for topping.
Mix together apples, granulated sugar and cinnamon. Place in shallow 2-quart baking dish. Sprinkle cereal mixture evenly over apples.
Bake at 325° F about 45 minutes or until apples are tender and cereal mixture has browned. Serve warm with dollop of plain or vanilla yogurt, if desired.
Yield: 8 servings