Preheat your oven to 350 degrees F. Grease a 9-inch cake pan or springform pan with Pam’s Baking Spray. Line the bottom with parchment paper and spray the sides. Set aside.
In a small bowl, mix together the brown sugar and the cinnamon until combined. Set aside.
For The Cake:
In a bowl of a stand mixer fitted with the paddle attachment, or with a hand-held mixer, cream together the room temperature butter, vegetable oil, and granulated sugar on medium speed until light and fluffy, about 3 minutes.
With a rubber spatula, scrape down the sides and the bottom of the bowl. On medium speed, beat in the eggs one at a time for 30 seconds each, scraping after each addition. Add the pure vanilla extract and whole-fat sour cream and mix on low just until combined.
In a separate bowl, whisk together salt, ground cinnamon, baking powder, and all-purpose flour.
With the mixer on low, gradually add the dry ingredients to wet ingredients. Mix until just combined. Do not overmix.
Pour batter into prepared cake pan and using the back of the spoon spread evenly across the top.
Evenly sprinkle the brown sugar mixture across the top, leaving room along the edges. Set aside while you make the gooey butter topping.
For the Cream Cheese Filling:
In a medium-sized bowl, use a hand mixer on medium-high speed to beat the cream cheese until it’s smooth and creamy.
Add the egg and mix on high for 30 seconds, using a rubber spatula to scrape the sides and bottom of the bowl.
Add the cinnamon, then gradually add 1 cup of powdered sugar at a time, mixing for 15-20 seconds after each addition!
Once combined, pour the cream cheese mixture on top of the cinnamon cake batter and use a small offset spatula to spread it into an even layer.
Bake for 40-45 minutes. The middle of the cake will still be slightly jiggly, but it's done when the edges are golden and the middle has cracked.
When the cake is done, let it cool for 10-15 minutes, then place it in the fridge to chill for at least 2 hours to allow the cream cheese to firm up and set.