Preheat the oven to 350°F (175°C). Grease and flour a 15x10-inch jelly roll pan.

In a large mixing bowl, combine granulated sugar, brown sugar, and vegetable oil. Mix until well combined.

Add the eggs one at a time, mixing well after each addition. Stir in the pumpkin puree.

In another bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Stir in the vanilla extract.

Pour the batter into the prepared jelly roll pan and spread it evenly.

Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Allow to cool completely in the pan.

In a medium bowl, beat together the softened cream cheese and unsalted butter until creamy and smooth.

Gradually add the powdered sugar, and mix until well combined. Add milk and vanilla extract, and mix until smooth and spreadable.

Once the pumpkin bars have cooled, spread the cream cheese frosting evenly over the top. Cut into bars and serve.