I made the whole recipe for the Bundt cake, but it makes a LOT of cake. When I make it the original way with no cream cheese layer, it makes so much that I put some of the batter in ramekins and there's still plenty for the Bundt cake. When I added this cream cheese layer, I put some of the batter (no cream cheese layer) in 1 regular loaf pan and 1 small loaf pan and then used the rest of the batter for this cake. So it would probably be fine to cut the ingredients in half and you'd have plenty of chocolate cake, but I haven't tried that yet so I can't say for sure.
Chocolate Sour Cream Bundt Cake with Cream Cheese Layer
1 c. cocoa powder, sifted, plus more for dusting pan
7 1/2 oz. semisweet chocolate, finely chopped
1 c. boiling water
2 1/4 c. all-purpose flour
1 1/2 t. baking soda
1 1/4 t. kosher salt
1 1/4 c. (2 1/2 sticks) unsalted butter
2 1/2 c. firmly packed light brown sugar
5 eggs, lightly beaten
4 t. vanilla extract
1 1/2 c. sour cream
1 1/2 c. semisweet chocolate chips
Cream Cheese Layer:
1 (8-oz.) pkg. cream cheese
1 T. butter
1 (14-oz.) can sweetened condensed milk
1 t. almond extract or vanilla extract
6 oz. semisweet chocolate, finely chopped
2 T. unsalted butter
1/2 c. heavy cream
Have all cake and cream cheese layer ingredients at room temperature.
Preheat an oven to 325°. Grease the Bundt cake pan and dust with cocoa powder; tap out the excess.
To make the cake, in a bowl, combine the 1 cup cocoa powder and the chocolate. Add the boiling water and whisk until the chocolate melts and the mixture is smooth and blended. Set aside.
Over a sheet of parchment, sift together the flour, baking soda and salt. Set aside.
In the bowl of an electric mixer fitted with the flat beater, beat the butter on medium speed until smooth and creamy, 30 to 45 seconds. Reduce the speed to low, add the brown sugar and beat until blended. Increase the speed to medium and continue beating until the mixture is light and fluffy, about 5 minutes, stopping the mixer occasionally to scrape down the sides of the bowl. Add the eggs a little at a time, beating until incorporated before adding more and stopping the mixer occasionally to scrape down the sides of the bowl. Beat in the vanilla until incorporated, about 1 minute.
Reduce the speed to low and add the flour mixture in three additions, alternating with the sour cream and beginning and ending with the flour, beating just until blended and no lumps of flour remain. Slowly pour in the chocolate-cocoa mixture and beat until no white streaks are visible, stopping the mixer occasionally to scrape down the sides of the bowl. Using a rubber spatula, gently fold in the chocolate chips.
Pour the batter into the prepared pan, leaving 2 inches from the top of the cake batter to the op of the pan. Spread the batter so the sides are about 1 inch higher than the center. (Pour remaining batter in greased loaf pan or ramekins and bake until top is well baked and tester comes out clean. Time for these will depend on size of pan.)
Make cream cheese layer by beating cream cheese, butter and until fluffy. Slowly mix in sweetened condensed milk, egg and extract until smooth. Pour mixture over cake batter in Bundt pan. (It will sink to the bottom of the cake so when it's done, they layer will be at the top of the cake.)
Bake until a toothpick inserted into the center of the cake comes out with only a few moist crumbs attached to it, 60 to 65 minutes. Transfer the pan to a wire rack and let the cake cool upright in the pan for 15 minutes. Invert the pan onto the rack and lift off the pan. Let the cake cool completely, at least 1 hour.
Meanwhile make the ganache: In a heatproof bowl, combine the chocolate and butter. In a small saucepan over medium-high heat, bring the cream just to a boil. Immediately pour the cream over the chocolate and butter. Whisk until the melt and the mixture is smooth.