Preheat oven to 350 degrees F. Liberally grease a 10-cup Bundt pan with baking spray, preferably the kind with flour in it. Set aside.
In the bowl of a stand mixer, cream together the butter and cocoa powder until combined; mixture may be a little lumpy. Beat in the sugar until combined, followed by the eggs, one at a time, followed by the vanilla. Beat in the sour cream, baking soda, and salt until combined. Add in one cup of the flour, mixing well, followed by 1/2 cup of the stout beer. Repeat, beating on low speed, until combined and smooth.
Pour the batter into the prepared pan and smooth out the top. Bake for approximately 35-45 minutes or until a toothpick or cake tester inserted near the center comes out clean or with moist, not wet, crumbs. Cool completely in the pan before inverting on a wire rack.
In a medium bowl, pour the hot heavy cream over the chocolate chips. Let set for about 5 minutes, then gently stir until smooth and glossy. Pour the ganache evenly over the cake and let set, about 10 minutes, before cutting into slices.