Preheat oven to 350. Prepare a 13 x 9" pan with cooking spray and flour; set aside. To prepare cake, combine cake mix, egg whites, one cup water, two tablespoon oil, two teaspoons cinnamon, and nutmeg in a mixing bowl. Mix until moistened. Pour batter into prepared pan. Bake for 30 minutes. Meanwhile, for topping, combine granola, brown sugar, remaining cinnamon, and water in a small bowl. Dollop on top of hot cake. Broil six inches from heat for two minutes, or until bubbly.