Start by preheating your oven to 325°F then liberally spray 3 (8-inch) round cake pans with non-stick baking spray or grease and flour.
In your mixer bowl, add oil and butter and beat for 2 minutes on high speed. Slowly add in sugar and beat on high speed for an additional 4-5 minutes until very pale yellow and fluffy.
Next, add eggs, one at a time, combining well after each addition and scraping down the sides as needed.
Add in vanilla extract and mix.
Sift cake flour, baking powder, salt and baking soda into a medium sized bowl. Turn your mixer down to its lowest speed, and slowly add flour into batter in two increments then add baking powder, salt and baking soda. Be careful not to over beat.
Lastly, add sour cream and heavy cream and scrape down sides and mix until just combined and turn off mixer.
Evenly pour cake batter into prepared baking pans and place in oven to bake for 17-24 minutes or until a toothpick inserted into the center of the cake comes just barely clean but don't over bake!! I personally start checking the cakes around 16 minutes just to be sure since everyone's oven is different.
Remove cakes from oven and rest in pans for 10-15 minutes. Invert cakes from pans onto cooling racks until cooled.