Preheat the oven to 350 F/180 C. Line two 8-inch round cake pans with parchment paper on the bottoms and set them aside.
In a stand mixing bowl, combine the flour, sugar, brown sugar, baking soda, baking powder, salt, and espresso.
Add in the butter and mix for 3 minutes on low until it resembles coarse sand.
Add in the sour cream and oil. Mix on low speed for exactly one minute. It should be a very thick paste.
In a bowl with a spout, whisk together the eggs, milk, and vanilla. In a separate bowl, whisk together the HOT coffee and cocoa powder.
With the mixer running on low, slowly stream the egg mixture into the batter and mix until just combined. Then immediately follow with the coffee/cocoa mixture, mixing until just combined.
Scrape down the bottom of the bowl to make sure there are no streaks of pale batter.
Evenly distribute the chocolate batter into both cake pans. About 725 grams in each.
Bake for 33-36 minutes, or until a toothpick inserted into the center comes out mostly clean, with a few moist crumbs clinging to it.
Let the pans cool on a wire rack for 20 minutes, then run an offset spatula around the sides of the pan. Flip each pan over to release the cake. Allow them to continue cooling completely on the rack.