Preheat oven to 350 degrees F. Line a 9-inch cake pan with two pieces of crumpled up parchment paper. I wad them up like trash and then smooth them out. I find this makes it easier to mold them into the cake pan. If you prefer, you can also grease and flour the cake pan instead.
With a stand mixer fitted with paddle attachment (or hand mixer), beat together the softened butter, vegetable oil, eggs, 3/4 cup of sugar and vanilla extract. Start on low speed then increase to high speed. Beat until pale and fluffy, 2 - 3 minutes.
Add the pumpkin and sour cream and beat again until smooth. In a separate medium bowl, whisk together the flour, baking powder, baking soda, salt, pumpkin pie spice and tablespoon of instant espresso. Add the dry ingredients to the wet ingredient mixture. Start the mixer on low speed and then increase to medium. Scrape down the bowl as needed. Mix just until the flour is incorporated.
Spread the pumpkin cake batter evenly into the prepared pan. Smooth the top with an offset spatula. Stir together the remaining sugar and tablespoon of espresso. Sprinkle it evenly over top of the cake.
Bake at 350 for 35 minutes, until a toothpick inserted into the center of the cake comes out clean. Let the cake cool in the pan for 10 - 15 minutes. Then gently lift it out of the pan using the parchment paper overhang. And allow to cool on a wire cooling rack for at least one hour before slicing. Be sure to serve each slice with a generous dollop of whipped cream.