• Preheat oven to 350°F. Set an ungreased 15x10 jelly roll pan onto a 17x12 rimmed baking sheet.
• Cream the granulated sugar and butter on medium speed until fluffy. Add the eggs one at a time until incorporated. Add the vanilla and beat well.
  400 grams granulated sugar, 1 cup unsalted butter, 4 large eggs, 1 teaspoon pure vanilla extract
• Whisk together the flour, baking powder, cinnamon, pumpkin pie spice, and salt. Turn the mixer to its lowest setting and add the flour mixture to the butter and sugar mixture slowly until completely combined.
  395 grams unbleached all purpose flour, 5 grams baking powder, 2 teaspoons ground cinnamon, 1 teaspoon pumpkin pie spice, 1/2 teaspoon salt
• In another bowl, whisk the canned pumpkin pie mix, 2 eggs, and pumpkin pie spice until smooth.
  30 ounces canned pumpkin pie mix, 2 large eggs, 1 teaspoon pumpkin pie spice
• Spread half the batter (weigh for even halves) into the pan. Spread the pumpkin filling evenly over the batter, all the way to the edges. Drop the remaining batter over the filling in small spoonfuls, roughly 1-2 tablespoon-sized, spaced out. Don't try to cover the filling completely. You want those gaps.
• Bake 55-60 minutes. The top should be golden brown and the center should not jiggle when you shake the pan. Do not under bake.
• Cool completely on a wire rack. The bars must be fully cool before drizzling or the cream cheese will melt and run.

To Make the Drizzle

• Beat the cream cheese and butter until smooth. Add the powdered sugar in two additions, then the vanilla, and beat until light. Add milk a couple tablespoons at a time until you reach the desired consistency. I use all 8 tablespoons.
  4 ounces cream cheese, 4 Tablespoons unsalted butter, 85 grams powdered sugar, 1 teaspoon pure vanilla extract, 8 Tablespoons milk
• Use a spoon or fork to drizzle lines across the cooled bars. If you like, you can place the pan in the refrigerator for 30 minutes to help speed up the setting of the drizzle. It will still remain fairly soft. Cut into squares.