To make cake:

1. Preheat the oven to 350 degrees F.
2. Coat a Bundt pan with cooking spray.
3. In a small bowl, whisk together baking mix and cocoa.
4. In bowl of a stand mixer, beat sugar, butter and oil until well blended and lighter in color. Beat in eggs one at a time.
5. Beat in cocoa mixture and water alternately, beginning and ending with cocoa mixture. 
6. Spread batter into the prepared pan.
7. Bake at 350 degrees F for 30 minutes or until wooden pick inserted in cake comes out clean. 
8. Remove cake from the oven and let cool in pan on a wire rack. Once mostly cool invert onto serving plate. 

To make ganache: 

1. Combine chocolate and 1/2 cup heavy cream in a microwave-safe bowl; microwave on HIGH in 30 second intervals and stir after each interval (be careful not to overcook.) 
2. Once melted and smooth, whisk in 1/2 cup powdered sugar. Add enough remaining cream and sugar to achieve smooth ganache consistency and desired degree of sweetness. Drizzle over cake.