Preheat oven to 325. F
Line an 8 x 8 glass pan with greased parchment paper. Set aside.
In a large bowl stir together granulated sugar, brown sugar, and butter.
Mix in eggs, and vanilla extract.
In a separate bowl, sift together flour, unsweetened cocoa powder, and salt.
Add the dry ingredients into the wet ingredients.
Stir just until dry ingredients are fully incorporated.
Remove 1/4 cup of the brownie batter and place it into a bowl.
Mix in 2 teaspoons of water into the reserved brownie mixture to thin it out a bit. Set aside.
Spoon the rest of the batter into the prepared pan and smooth out into an even layer.
To make the cream cheese mixture, in a large bowl, cream together cream cheese and egg.
Mix in sour cream, powdered sugar, and vanilla extract until creamy.
Carefully spread the cream cheese layer on top of the brownie batter.
Drop the reserved brownie mixture on top of the cream cheese layer in several circle dallops.
Use a knife to lightly swirl the thinned brownie batter into the cream cheese layer to create a marbled effect.
Bake for 35-40 minutes or until the center is set and a toothpick inserted into the center comes out clean(The center will be slightly jiggly).
Let cool on a cooling rack and then refrigerate for an hour or until firm.
Cut into small bars and serve.
Store in the fridge.