Preheat oven to 325 degrees.  Place the oven rack on the lower middle level.  Spray a bundt pan with vegetable oil or non-stick cooking spray, set aside.

In a large bowl whisk together the dry ingredients.  Add the flour, salt, and baking soda, whisking until fully incorporated, set aside.

In a small heat-proof bowl add the cocoa powder, 6 ounces of chocolate, and espresso powder.  Carefully add the boiling water, whisking until chocolate is melted and mixture is thoroughly incorporated, set aside.

In the bowl of a stand mixer, fitted with the paddle attachment, beat the butter, brown sugar, and vanilla on medium speed until light and fluffy, 3-4 minutes.  Add the eggs one at a time, beating for 30-40 seconds after each addition.  Scrape down the bowl and the paddle.

Add the chocolate mixture, mixing on medium low until combined, 30-40 seconds.  Add half of the flour mixture, mix on low until just incorporated, 20-30 seconds

Add the sour cream, mixing on medium speed until combined, 30 seconds.  Add the second half of the flour mixture, mix on low until just combined.  Scrape down the bowl and paddle, mix on medium speed to fully incorporate batter, 30-40 seconds.

Pour batter into prepared bundt pan, smoothing the surface into an even layer.  Bake cake for 50 minutes or until a toothpick inserted in the center comes out clean.  Remove cake from oven and cool in the pan on a wire rack for 10 minutes.  Invert cake onto a second wire rack, place a room temperature to cool for 1 hour.

While the cake is baking prepare the ganache.  In a small saucepan over medium heat, bring the ½ cup of cream to a simmer, do not boil.  Pour cream over 4 ounces of chopped chocolate.  Allow to set for a minute then stir to incorporate and melt the chocolate, set aside to cool.

Place the cooled cake on the desired serving dish, top side down.  Pour ganache evenly over the cake, allowing any excess to flow down the sides of the cake.  If the ganache firms up and does not pour, microwave for 5-10 seconds to loosen slightly.  Continue to cool cake for another hour before serving.