Preheat oven to 350 degrees. Generously spray a 12 cup bundt pan with nonstick cooking spray.
In a large mixing bowl, add cake mix, sugar, sour cream, and oil and mix on low speed for 1 minute.
Add the eggs, one at a time, blending well after each addition.
Increase mixer speed to medium and beat for 4 minutes.
Add vanilla and chocolate chips and mix on low speed until the chips are evenly distributed.
Pour the batter into prepared pan and bake in preheated oven 60-65 minutes or until a tester inserted into the middle of cake comes out clean.
Allow cake to cool in pan then invert onto a cake plate.
When cake is cooled, make ganache.
In a glass bowl, combine the chocolate and butter.
In a small saucepan over medium-high heat, bring the cream to a boil. While cream is heating, microwave chocolate and butter for 30 seconds at 100% power. Immediately pour the cream over the chocolate and butter. Whisk until the mixture melts and becomes smooth.
Pour the ganache over the top of the cake. Allow the ganache to set for about 20 minutes, then cut cake and serve.