Preheat your oven to 350 degrees. Spray a 9 by 13 inch baking dish with cooking spray. Set aside
In a large bowl whisk together the flour, baking powder, baking soda, salt, and spices. For best results, sift the dry ingredients to fully combine. Read more about sifting here.
In a smaller bowl mix together the pumpkin, eggs, oil, and sugar. Gently fold the wet ingredients into the dry ingredients, until completely smooth.
Pour in the prepared baking dish and bake for 25 to 30 minutes or until a toothpick inserted into the middle of the cake comes out with just a few crumbs.
Allow the cake to cool compltely before frosting.
To make frosting, beat together the cream cheese and butter until smooth. Add in the powdered sugar and beat until full combined. Then beat in the vanilla.
Smooth the frosting over the cake with an offset spatula. Cut and serve.