Preheat oven to 350 degrees F. Spray a 12-cup Bundt pan with cooking spray and set aside.
In a large bowl, combine sour cream, dry instant pudding mix, cake mix, water, oil, and eggs with an electric mixer on medium speed for about 1-2 minutes, or until thick and smooth.
Use a wooden spoon or a spatula to gently fold in the chocolate chips.
Pour batter into prepared Bundt pan.
Bake for 45 minutes – 1 hour, or until a toothpick inserted in the center of the cake comes out clean.
Let cake stand for 12 minutes. Invert on a cooling rack and remove cake from pan.
Once cake is completely cool, dust with powdered sugar.
Note: This cake can be baked in advance, wrapped tightly, and frozen for up to 3 months. Do not dust with powdered sugar until ready to serve.