Preheat your oven to 350℉. Prepare a 15x10x1-inch baking pan by spraying it with nonstick spray.
In a large bowl, cream together 2 cups of granulated white sugar, 1 cup of salted butter, and ½ teaspoon of salt using an electric mixer. Mix until the mixture is light and fluffy.
Next, add in the 4 large eggs, one at a time, beating well after each addition. This step is crucial for incorporating air into the batter.
Once the eggs are well mixed in, add 1 teaspoon of vanilla extract and mix until everything is combined.
Gradually add in 3 cups of all-purpose flour, mixing just until combined.
Spread approximately 3 cups of this dough into the prepared baking pan.
Open the can of pumpkin pie mix and spread it evenly over the dough in the pan.
Using a spoon, drop teaspoonfuls of the remaining dough over the pumpkin filling, creating a topping layer.
Place the pan in the preheated oven and bake for 30 to 35 minutes, or until the top is golden brown.
Once baked, allow the bars to cool in the pan on a wire rack.
In a medium bowl, whisk together the glaze ingredients: 1 cup of powdered sugar, ½ teaspoon of vanilla extract, and 2 to 3 tablespoons of milk.
Once the bars are cool, drizzle the glaze over the top, ensuring it settles into all the nooks and crannies.