Preheat the oven to 350°F. Grease a 9x13-inch baking dish or line with parchment paper.
In a large bowl, whisk together the pumpkin puree, vegetable oil, granulated sugar, brown sugar, eggs, and vanilla until smooth.
In a separate bowl, whisk together the flour, baking powder, baking soda, cinnamon, pumpkin pie spice, and salt.
Add the dry ingredients to the pumpkin mixture and stir just until combined.
Pour the batter into the prepared baking dish and spread evenly.
Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bars to cool completely.
Beat the softened cream cheese and butter together until smooth and fluffy.
Gradually beat in the powdered sugar. Add the vanilla and salt and continue beating until smooth.
Spread the cream cheese frosting over the cooled pumpkin bars.
Slice into 24 bars and serve.