Heat oven to 350°F, position the oven rack to the middle position, and spray a rimmed sheet pan (11x15) with nonstick baking spray.
In a large mixing bowl, whisk together flour, baking powder, baking soda, salt, cinnamon and pie spice. Set aside.
In the bowl of a stand mixer, combine sugar and oil. Mix on medium speed until well incorporated, about 1 minute.
Add eggs one-at-a-time (mixing well after each addition).
Add pumpkin and mix 1 minute.
Set the mixer to the lowest speed and add the flour (1 cup at-a-timuntil no flour is visible. Turn mixer to medium speed and beat 1-2 minutes or until smooth and flour is completely incorporated.
Pour the pumpkin batter into the prepared pan and rap the pan on the counter to release any batter bubbles.
Bake 25-33 minutes or until a toothpick inserted in the middle comes out clean.
Transfer the cake to a wire cooling rack to cool completely.
When the cake has cooled, frost with Best-Ever Cream Cheese Frosting.
Keep cake refrigerated (and covereup to 3 days.
For the Frosting:
Place cream cheese in the bowl of a stand mixer and mix on medium-high speed for 1 minute.
Add butter and mix another 1 minute or until incorporated.
Add sour cream, vanilla extract and salt; reduce speed to medium and beat an additional 1minute.
Add the confectioner’s sugar and beat 2-3 minutes or until the frosting is fluffy, smooth and the powdered sugar is dissolved.
*Note: The frosting can be made up to 2 days ahead. Keep refrigerated and in an airtight container until ready to use. When ready to use, place the frosting in a mixing bowl and mix on medium speed about 1-2 minutes or until fluffy and refreshed.