1Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10x13-inch baking dish.
2Beat cream cheese, 1/3 cup sugar, and 1 egg together in a bowl using an electric mixer until smooth.
3Mix water, cocoa powder, and butter together in a saucepan; heat over medium-low heat until melted, about 5 minutes.
4Combine flour, remaining 2 cups sugar, 2 eggs, sour cream, baking soda, vanilla extract, and salt in a large bowl. Beat chocolate mixture into flour mixture until batter is smooth; spread into the prepared baking dish. Spoon cream mixture over batter and run a knife through the cream cheese mixture to spread into a marbled pattern. Sprinkle butterscotch chips over top.
5Bake in the preheated oven until the top is dry and the edges have started to pull away from the sides of the pan, about 35 minutes.
Footnotes
Cook's Notes:
In the picture, the cream cheese is not as "swirly" as it could be, but you get the idea. I forgot to butter and flour the pan one time but had sprayed with Pam(R) - they came out fine but stuck a little more to the pan.