Preheat the oven to 325 degrees F. In a large bowl, whisk together cake mix and cinnamon. Add pumpkin puree, eggs and water. Mix well until you have a smooth texture.
Pour batter into a bundt pan sprayed with non stick spray (mine was a 10.5 inch pan).
Bake for approximately 40-45 minutes or until toothpick comes out with moist crumbs attached but batter is not still wet, do not over-bake.
Remove and let cool before turning putting a large plate or platter on top and carefully flipping it over to slide out.
While the cake is baking, mix together the ingredients for the cream cheese frosting. Spread on top once flipped over when it is cool, slice and enjoy.