1. Preheat the oven to 350 degrees and spray a 9x13 baking dish with non-stick baking cooking spray.

Chocolate Cake Batter

1. Whisk together the sugar, flour, cocoa, baking powder, baking soda and salt.
2. Whisk together the sour cream and milk.  Beat into the dry ingredients with the eggs, vegetable oil, and vanilla.  Beat at a medium speed for 1 minute.
3. Carefully beat in the boiling water and beat until blended and smooth.  Set aside and prepare the cheesecake batter.

Cheesecake Batter

1. Beat cream cheese and sugar until fluffy.  Beat in the milk, egg and vanilla until smooth.

Assembly

1. Pour 1/2 the cake batter into the prepared baking dish.
2. Pour 1/2 the cheesecake batter in thick stripes across the top of the cake batter.  (See photos in the post for this recipe)
3. Pour the remaining cake batter over the top of the cheesecake stripes.
4. Pour the remaining cheesecake batter in thick stripes across the top of the cake batter.
5. Using a knife, moving from one end of the dish to the other in figure eight motions swirl the cheesecake batter and the cake batter.  Start on one side of the pan and end at the other.  Do not continue to swirl after this or the cheesecake with just blend in with the cake and you will not get the swirled, marble effect.
6. Bake at 350 degrees for 45-50 minutes.  A toothpick should come out with moist crumbs.
7. Cool completely and then refrigerate for 4 hours before cutting and serving.

Chocolate Cream Cheese Frosting

1. Beat the cream cheese and butter until blended and smooth.
2. Beat in the cocoa powder until smooth.
3. Beat in 2 1/2 cups of the powdered sugar.  If you want a stiff frosting add another 1/2 cup of powdered sugar.
4. Either spread across the top of the cake or pipe onto individual pieces.  I used a Wilton 1M tip.