In a large bowl, beat the egg, egg whites, buttermilk, oil, applesauce and molasses. Combine the flour, brown sugar, baking soda, spices, baking powder and salt; add to egg mixture and mix well. Pour into a 13-in. x 9-in. baking pan coated with cooking spray.
For topping, combine the brown sugar, flour and spices in a bowl; cut in butter until mixture resembles coarse crumbs. Sprinkle over batter. Bake at 350° for 35-40 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack. Yield: 18 servings.