Moist and tender cake topped with ganache frosting
Preheat oven to 340F (165C) and line an 8-inch or 9-inch pan with parchment paper.
Pour the hot coffee over the chopped chocolate and cocoa powder, in a medium bowl. Give it a minutes or two to sit, then gently stir until smooth.
Mix in the sour cream and set aside.
mix the flour, baking powder, baking soda, and salt in a separate bowl. Set aside.
Beat the butter, oil, and sugar in a bowl of a stand mixer until light and fluffy, about 4-5 minutes. Scrape the bottom and sides of the bowl.
Add the eggs, one at a time, waiting for the first egg to be fully incorporated before adding the next.
Lower the speed to low, then add the flour mixture in three additions alternating with the cocoa mixture.
Once you added the last portion of the flour, turn the mixer off and use a rubber spatula to incorporate any chocolate residue.
Pour the batter into the prepared pan, use an offset spatula to smooth the top, and bake for 38-45 minutes if using an 8-inch, or 35-40 minutes if using a 9-inch.
Place the chopped chocolate in a medium bowl.
Over the stove, heat the cream and sugar to a simmer while stirring.
Pour the cream mixture over the chocolate and set aside for about 5 minutes.
Slowly stir the chocolate and cream until smooth and shiny.
Let cool. As it cools it will get a paste-like texture.