Prepare cream cheese filling: In a small mixing bowl, beat ¼ cup sugar and cream cheese until smooth. Add one egg and 1 teaspoon vanilla, and beat at low speed until combine; set aside.
Preheat to 350°. Butter and flour a 12-cup Bundt pan or spray with non-stick cooking spray with flour.
In a small saucepan, combine the butter, cocoa powder, salt, and water. Cook over medium heat stirring constantly until butter is melted and cocoa is dissolved. Remove from the heat and set aside.
In a large mixing bowl, combine the flour, sugar, and baking soda. On low speed, gradually mix in butter mixture. Add the eggs one at a time and mix until incorporated. Mix in the sour cream and vanilla until batter is smooth.
Pour half of the batter evenly in to the prepared bundt pan. Dollop the filling around the middle of the bundt. Drag a butter knife through the cheesecake filling to swirl some chocolate batter into the cheesecake filling being careful not to let the cheesecake filling touch the side of the pan. Pour the other half of the batter on top of the cheesecake filling and if necessary, spread evenly around pan.
Bake at 350º for 50 – 60 minutes or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes and then invert onto a rack to cool completely before adding ganache.
Chocolate Ganache
Place half of the chocolate in a mixing bowl. Heat heavy cream on medium high heat until it comes to a boil.
Remove from heat and immediately pour cream over chocolate and stir until chocolate is completely melted. Add remain chocolate and stir until chocolate is completely melted.
Cool until ganache is thickened but still thin enough to drip down the sides of the cake. (I cooled mine in the fridge for over 2 hours.)