Preheat oven to 325° F and spray (or butter) 3 6" round cake pans with nonstick cooking spray.
In a small bowl, melt chocolate chips in microwave; heating for 30 seconds at a time and stirring in between until chips are completely melted. Stir in 1/4 cup of the vegetable oil.
In large mixing bowl, or stand mixer, combine remaining eggs, oil, and sour cream. Add sugar, cocoa powder, baking soda, baking powder, and salt and mix to combine.
Stir in melted chocolate chip/oil mixture and then stir in flour. Make sure to not over-mix.
Divide mixture evenly among prepared baking pans and bake at 325° F for 50-60 minutes or until toothpick inserted in center comes out clean.
Remove from oven and let cool in pans for 15 minutes then invert onto cooling rack to cool completely.
Frosting
While cakes are baking and cooling, add about 2 cups of Oreo cookies to food processor and process until they are fine crumbs.
In a large bowl with electric beaters, or the bowl of a stand mixer, add cream cheese and butter and cream together until fluffy.
Add vanilla extract and mix to combine. Mix in powdered sugar, 1 cup at a time until fully incorporated.
Add crushed Oreo cookies and turn mixer to high and beat until stiff and desired thickness.