Preheat oven to 375 degrees Fahrenheit and line the bottom of two 9-inch cake pans with parchment paper. Grease and flour the pans.
Whisk dry ingredients (flour, cocoa powder, espresso powder, baking powder, baking soda, and salt) together in a medium sized mixing bowl.
Beat oil and sugars together until well incorporated.
Add eggs one at a time, beating until incorporated after each addition.
Scrape down sides of bowl and add vanilla, mix until just combined.
Alternate adding 1/3 of the flour mixture and 1/2 of the buttermilk to the mixing bowl, starting and ending with the flour. You will have three additions of flour and two additions of buttermilk. Scrape down the sides as needed and mix until incorporated after each addition.
Add hot water and mix until just combined with a rubber spatula.
Distribute batter evenly among the two cake pans, then transfer to oven.
Bake at 375 degrees for 22-25 minutes, or until a toothpick inserted into the center of each cake comes out with only a few moist crumbs attached.
Let cakes cool in pan for about 15 minutes, then turn out onto a wire cooling rack and let cool completely.
Frost and decorate as desired.
*Make your own buttermilk by measuring out a scant one cup milk (2% or whole), then adding about 1 tablespoon of vinegar or lemon juice. Stir and let sit for 5 minutes before using.