Preheat oven to 350F. Line the bottom of each cake pan with parchment paper.
Whisk together the flour, baking soda, and salt in a bowl and set aside.
In a bowl of a stand mixer fitted with the paddle attachment, cream together the butter, oil, both sugars, molasses and all of the spices until light and fluffy at medium high speed.
On low speed, add the eggs two at a time just until incorporated. It is really important to stop the mixer and scrape down the sides and bottom of the bowl in between each addition!
Still on low speed, add the dry ingredients in four parts, alternating with the pumpkin puree in three parts.
Bake for 1 hour and 30 minutes, or until a toothpick inserted in the center comes out clean, rotating the pan(s) halfway through.
Transfer to a wire rack and let cool completely in the pan(s). Cover tightly with plastic wrap and refrigerate overnight. Loosen the edges with a straight spatula, invert the pan(s) to remove the cake, and peel off the parchment.