Beat ⅓ cup vegetable oil, 2 large eggs, ½ cup white sugar and ½ cup brown sugar for 2 minutes in a large mixing bowl until thick and light-colored.
Add 1 cup pumpkin puree, 2 teaspoons pumpkin pie spice mix and ½ teaspoon vanilla extract. Mix well.
Add the sifted dry ingredients (1 ½ cups all-purpose flour, 1 teaspoon baking powder, ½ teaspoon baking soda and ¼ teaspoon salt) and mix until well incorporated, but don't overbeat. This is the time to mix at the lowest speed of the beater or use a spatula. You can sift the dry ingredients separately and then add them to the pumpkin mixture, or have them measured and sift them directly over the cake batter (like I do).
Spread the pumpkin cake batter in the prepared pan.
Bake for about 35 minutes or until a cake tester or toothpick comes out clean. Don't overbake it so the cake is moist and tender.
Let cool for 15 minutes on a wire rack. Make sure there is no cake stuck to the sides of the pan where there's no parchment paper. If there is, run a smooth-bladed knife to loosen them.
Remove the cake by lifting the paper on both sides and transferring it to the cooling rack. Carefully remove the paper and let the cake cool completely before frosting.
Frost with the cream cheese frosting below using an offset spatula and cut into squares to eat.
Refrigerate leftovers well covered.