Mix all dry ingredients in a large mixing bowl. Add all remaining ingredients, except apple. Beat 1 minute. Stir in apple. Pour into a greased 9 x 13 inch pan. Mix the topping and sprinkle over the batter. Cover the pan and refrigerate overnight.
The next day, set the pan out on the counter while preheating oven to 350°. Bake 45-50 minutes. Turn off the oven, open the oven door and let the coffeecake cool in the oven. Cut into squares and serve while warm.