Preheat oven to 325 degrees. Grease and four a 10-12 cup bundt pan.
In a small bowl, beat ingredients for cream cheese filling until smooth. Set aside.
In a large bowl, with an electric mixer on medium speed, combine the cake mix, flour, water, vegetable oil, eggs and sour cream. Fold in the chocolate chips. Pour batter into the prepared pan.
Spoon cream cheese filling over batter, keeping it away from edge of pan. Run table knife through batter in large zigzag pattern once around the pan.
Bake for 45-50 minutes, or until toothpick inserted in center of cake comes out clean. Cool for 10-15 minutes in the pan before turning onto a wire rack to cool completely.
Meanwhile make the topping. In a small bowl, beat the cream cheese and milk. Mix in powdered sugar until smooth. Spoon over cake.
In a small microwave safe bowl, heat whipping cream on high for about 30 seconds or until it just begins to simmer. Add the mini chocolate chips and whisk until smooth. Drizzle chocolate over cream cheese frosting. Sprinkle with additional chocolate chips, if desired.