Preheat oven to 350° degrees F. Very liberally grease a Bundt pan with cooking spray, or rub the pan with shortening and dust with flour. You want it really well greased!
In a large bowl, combine the cake mix, dry pudding powder, eggs, oil, sour cream, and milk and beat with a handheld electric mixer until combined and smooth, about 1 minute. Stir in the white chocolate chips and the fresh cranberries.
Pour the batter into the prepared pan in an even layer. Bake for 50 minutes or until a toothpick inserted near the center comes out clean. Cool completely in the pan. Once cooled, gently invert the pan onto a wire rack with wax paper underneath to catch ganache drippings.
For the ganache, heat the heavy whipping cream in a microwave-safe bowl for 30-45 seconds or until hot to the touch. Add the chopped chocolate bars to the hot heavy cream and let stand for 5 minutes. Stir until smooth, then pour the ganache evenly over the top of the cake. Immediately sprinkle with the sweetened dried cranberries. Let ganache set, about 15 minutes, before serving.