Preheat oven to 350 degrees F (175 degrees C). Spray a large jelly roll pan with cooking spray or oil. Remove butter and cream cheese from refrigerator and set aside.
Beat eggs in a large bowl with an electric hand mixer until foamy; add the vegetable oil, pumpkin, and white sugar, Beat on medium speed until incorporated, about 2 minutes. Next, add the flour, baking powder, baking soda, 2 teaspoons cinnamon, and a pinch of salt. Beat on low speed until just combined, 1 minute. Pour batter into the prepared pan. Bake in the preheated oven until a toothpick inserted in the center of the cake comes out clean, about 25 minutes. Cool completely before frosting.
To Make the Frosting:
Beat cream cheese, butter, and vanilla together in a bowl with an electric hand mixer until creamy. Gradually add confectioners' sugar; beat until smooth. Spread frosting evenly over cooled pumpkin bars; sprinkle with cinnamon. Cover and store in fridge for up to 6 days. Serve cold. Enjoy!