Set the oven rack to the middle position. Heat the oven to 350ºF (177ºC).

Grease a 13 x 9-inch baking pan with cooking spray or vegetable oil. Add 1 tablespoon of flour to the pan, turn, and tap the pan to lightly coat the bottom and sides. Tap out any extra flour that remains in the pan.

In a medium bowl, whisk together 2 cups of sifted flour, pumpkin pie spice, baking powder, baking soda, and salt.

In a large bowl, vigorously whisk together granulated sugar, brown sugar, eggs, and vegetable oil, until thick and smooth, about 3 minutes. Add pumpkin puree and whisk until combined, about 15 seconds.

Fold the flour mixture into the pumpkin mixture and stir until no flour streaks and just a few small lumps remain. Do not overmix.

Evenly spread the pumpkin cake batter into the prepared baking pan. Bake for about 30 to 33 minutes, until a toothpick in the center comes out clean or the internal temperature reaches 195 to 200ºF (90 to 93ºC). Cool completely on a wire rack for about 1 ½ to 2 hours.

In a stand mixer fitted with a paddle or hand mixer, beat softened butter and powdered sugar on low speed until just incorporated. Gradually increase the speed to medium, beating until light and fluffy, about 1 to 1 ½ minutes.

Add half of the softened cream cheese and beat on medium speed until incorporated, about 15 seconds. Add the remainder of the cream cheese and beat until smooth, about 15 to 20 seconds.

Add the maple syrup and vanilla extract. Beat until the frosting is light and smooth, about 30 to 45 seconds.

Frost the cooled cake and sprinkle chopped nuts on top if desired. Slice and serve.