Yield: 18 servings (3 Freestyle points per serving)
Preheat oven to 350 degrees F.
In a mixing bowl add the pumpkin, evaporated milk, eggs, pumpkin pie spice, cinnamon, vanilla extract and granulated Splenda. Whisk together.
In a second mixing bowl add the cake mix and diet Sprite. Beat for 2 minutes on medium speed.
Spray a 9x13 baking pan with no-stick cooking spray. Add the pumpkin pie mixture, then add the cake mixture.
Bake 50 minutes. Let cool, then add the fat-free Cool Whip.