Preheat oven to 350°F and line a muffin tin with cupcake liners.
Place the softened butter, vegetable oil, sugar, and brown sugar in the bowl of a stand mixer fitted with the paddle attachment.
Cream the butter, oil, and sugars together on a medium speed (speed 4 for a kitchen aid mixer) for 5 minutes, until the butter and sugars are light and fluffy.
Add the whole eggs and yolks one at a time, mixing at a medium low speed until combined, and scraping down the sides of the bowl after each addition.
Add vanilla extract and pumpkin puree and mix until combined.
In a medium sized bowl, whisk together the flour, baking powder, salt, and pumpkin pie spice.
Next, add half of the dry mixture into the batter and mix together on a low speed until its almost combined.
Add all of the sour cream and mix until just combined.
Add the last half of the dry ingredients mixture and mix on a low speed until combined.
Using a muffin scoop, scoop the batter into the cupcake liners so they’re about ¾ of the way full.
Place the cupcakes in the oven and bake for about 15-20 minutes. You can also check doneness of the cupcakes by inserting a toothpick into the center of the cupcake and if the toothpick comes out clean your cupcakes are done :)
Let cupcakes cool at room temperature before frosting!