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, this will help prevent sticking.

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, 3 minutes. Add pumpkin puree and whisk until combined, 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 until a toothpick in the center comes out clean or the internal temperature reaches 195 to 200ºF (90 to 93ºC), about 30 to 33 minutes. 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 the mixture 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, scraping the bowl as needed, about 30 to 45 seconds.

The cake can be left in the pan and frosted or inverted onto a serving platter. Use a spatula to spread the cream cheese frosting over the cake evenly. Sprinkle the chopped nuts on top, if using, or other desired toppings. Slice and serve.