Preheat oven to 350F and grease a 10x15x1 inch jelly roll pan or line it with parchment paper.
Combine the flour, salt, baking soda, baking powder, and spices in a large bowl then whisk together and set aside.
In a separate bowl combine the eggs, oil, white and brown sugar, vanilla, milk, and pumpkin puree then whisk together until smooth.
Pour the wet mixture into the dry and mix until just combined then transfer the batter to your prepared pan and spread out into an even layer using an offset spatula. Bake at 350F for about 25 minutes or until the center springs back when pressed lightly.
Make the frosting by beating room temperature cream cheese and butte together until combined then add the powdered sugar and vanilla. Beat on low then switch to high for about three minutes or until light and creamy. scrape the bowl down and mix once more.
Once the base is cool cover with the cream cheese frosting, cut and serve. I like to garnish with a sprinkle of cinnamon but sprinkles
Video
Notes
Weigh the flour: Adding too much flour to the recipe is a common mistake and leads to dry, crumbly bars. The best way to measure flour is by using a scale. If you don’t have one, fluff your flour with a spoon, sprinkle it into your measuring cup, and use a knife to level it off.
Use room temperature ingredients: Bring your eggs, milk, butter, and cream cheese to room temperature to make them easier to incorporate.
Use pure canned pumpkin: Only use 100% pure pumpkin, not canned pumpkin pie filling. Pie filling has spices and sugar added to it, which affects how the pumpkin bars bake.
Don’t overmix the pumpkin batter: This causes too much gluten to develop, leading to pumpkin bars that are tough or too dense.
Let the bars cool before frosting: If the pumpkin bar base is still warm, the frosting will melt.