Preheat the oven to 350 degrees. Line a 9x13 baking pan with parchment paper.
In a large bowl, add the chocolate cake mix, butter, and using a hand mixer, mix until the butter is incorporated.
Add in 2 of the eggs and mix until combined.The batter will be thick.
Press the dough evenly into the bottom of the prepared baking pan and set aside.
In a medium bowl, add the softened cream cheese, powdered sugar, 2 remaining eggs, cocoa powder, and vanilla, and using a hand mixer, mix until combined.
Pour the cream cheese layer evenly over the dough.
Bake for 40 minutes, remove from the oven allow to cool before cutting.
Notes
Store leftovers in an airtight container in the refrigerator.Don’t overbake them. The center should still look slightly soft and jiggly when you take the bars out of the oven. They’ll continue to set as they cool.