Preheat the oven to 350 degrees F. Prepare a rimmed cookie sheet (13"x18") by lining with parchment paper or spray with nonstick cooking spray. Set aside.
In a medium mixing bowl, whisk together the dry ingredients; flour, pumpkin pie spice, baking powder, baking soda, and kosher salt.
3 cups all-purpose flour, 1 tablespoon pumpkin pie spice, 1 teaspoon baking powder, 1 teaspoon baking soda, 1 teaspoon kosher salt
In a larger mixing bowl, whisk together the eggs, pure pumpkin, light brown sugar, vegetable oil, granulated sugar, maple syrup, and vanilla extract until well combined and smooth.
2 large eggs, 1 can (15 oz) pure pumpkin, 1 cup packed light brown sugar, 1 cup vegetable oil, 1/2 cup granulated sugar, 2 tablespoons pure maple syrup, 1 teaspoon vanilla extract
Next, add the dry ingredients into the wet ingredients. Mix thoroughly, with a silicone rubber spatula, until combined but be sure not to overmix the batter. Allow the batter to rest for 10 minutes.
Use a 3 tablespoon cookie scoop (a large cookie scoop) to scoop the dough onto the prepared cookie sheet. Bake for 10-12 minutes.
Remove cookies from the oven and allow them to cool completely before filling them. *Let the cookies cool on the warm cookie sheet for about 10-15 minutes and then remove them to a cooling rack to finish cooling completely. While the cookies are baking make the filling so it has time to refrigerate. In a mixing bowl using an electric hand mixer, beat the cream cheese, granulated sugar, and vanilla extract until creamy and no lumps remain. Stir in the thawed Cool whip and mix until combined. Cover the bowl and let the filling refrigerate until you're ready to fill the whoopie pies. 1 bar (8 oz) cream cheese, 2/3 cup granulated sugar, 2 teaspoons vanilla extract, 8 ounces Cool Whip
When ready to fill, place the cream cheese filling inside a piping bag with a large 1A tip OR you can put it inside a gallon-sized Ziploc bag with the corner snipped off. Flip half of the cookies over and pipe a generous amount of filling onto each flipped over half. Place the other cookie on top and press together gently.
The whoopie pies are best served chilled from the fridge so I recommend storing them inside a covered container for at least 2-3 hours before serving.