Preheat oven to 335° F. Prepare cake pans with nonstick cooking spray and parchment circles.
In a large mixing bowl, whisk together all-purpose flour, baking powder, salt, and pumpkin pie spice. Set aside.
In a separate large mixing bowl, combine light brown sugar, granulated sugar, vegetable oil, eggs, and vanilla extract. Whisk until well combined.
Add in pumpkin puree and sour cream. Whisk until smooth.
Pour the dry ingredients into the wet ingredients and whisk gently until the batter is smooth and there are no lumps.
Portion the batter evenly into the prepared cake pans (See equipment or blog post for sizes). Spread the cake batter using an offset spatula.
Bake the cake layers for approximately 35 minutes until they bounce back when gently touched or an inserted toothpick comes out clean. Baking times may vary depending on what size cake pans you use.
Remove the cake layers from the oven and allow the cakes to cool in the pan for 15 minutes.
Remove the cake from the pan and transfer to a wire rack to cool completely. Level the cake layers using a serrated knife.