Preheat the oven to 350 degrees, then mist a 9x13 inch pan with cooking spray.
In a large bowl, whisk together the flour, baking powder, kosher salt, baking soda, cinnamon, ginger, cardamom, and nutmeg, then set it aside.
In a stand mixer bowl, add the pumpkin puree, granulated sugar, and the light brown sugar. Fit the stand mixer with the paddle attachment and bump the speed up to medium low and let mix for 2 minutes.
In a spouted measuring cup, whisk together the vegetable oil, buttermilk and eggs.
Bump the stand mixer speed down to low, then alternate between adding the flour mixture (⅓ cup at a time) and the egg mixture.
Once all of the flour and egg mixture has been added. Scrape down the sides and bottom of the stand mixer bowl, and let the batter mix on medium-low speed for a final 30 seconds.
Pour the pumpkin cake batter into the prepared pan, and bake for 26-30 minutes. Until a toothpick inserted into the center of the cake comes out clean.
Once the cake is done baking, let it cool completely at room temperature, about 1-2 hours.