Center a rack in the oven and preheat to 350 (F). Prepare three 8-inch cake pans by spraying generously with cooking spray and lining the bottoms with a parchment paper circle round; spray the parchment paper as well and set aside.
In a medium bowl, whisk together 2 cups all-purpose flour, 3/4 cup Dutch-processed cocoa powder, 2 teaspoons baking soda, 2 teaspoons espresso powder, and 1 teaspoon kosher salt. Set aside.
In a large bowl, whisk together 1 cup sour cream, 2 teaspoons pure vanilla extract, 1/2 cup canola oil, 1 1/2 cups tightly packed dark brown sugar, 1/2 cup granulated sugar and 2 large eggs until very well combined.
Sprinkle the dry ingredients (from the 2nd step) over the wet ingredients (from the 3rd step) and whisk until the dry ingredients are just incorporated into the wet ingredients — don't worry about any lumps or streaks of dry ingredients at this point. Whisk in 1 cup boiling water, 1/4 cup at a time, until all of the water is incorporated and you have a nice, smooth batter — the batter will be a little thin, but that's okay. Divide the batter evenly between the prepared pans.
Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center of each cake comes out with just a few crumbs. Transfer to a wire rack and cool completely before frosting.