Preheat oven to 350° F. Prepare four to five 7" x 2" round cake pans - I use cake release to prevent sticking.
Melt butter in a large saucepan over medium-low heat; add cocoa, stirring until smooth. Whisk in the espresso water and remove from heat.
Add the sugar, sour cream, vanilla, and eggs to the warmed cocoa mixture and whisk until smooth.
In a medium bowl, combine the flour, baking soda, and salt. Add to the first mixture, whisking until well blended.
Pour batter into the prepared pans. Bake for 30-35 minutes, or until it feels firm to the touch or an inserted toothpick comes out clean. Cool in pan on a rack for about 15 minutes.
Remove from pan by placing the rack over the cake and invert, tapping pan lightly, if required to loosen.
To make the frosting:
Mix vanilla and espresso powder together until dissolved. Using the whisk attachment of your mixer, whisk for 5 minutes, occasionally scraping down sides. On low speed, add powdered sugar a little at a time. I cover the mixer with a damp tea towel to contain the powdered sugar. When all powdered sugar is incorporated, turn up speed and beat until fluffy for about 2 minutes. Add vanilla-espresso mixture and whip until incorporated.
Assembly:
Level the cakes using a large, serrated knife or other levelling tool (I use the Agbay Jr.). Fill each layer with generous amounts of frosting, wrap win plastic wrap and refrigerate for an hour. I find this helps the cake to settle and level itself and makes crumb-coating easier. Remove from fridge, add a thing layer of frosting refrigerate for 30 minutes and repeat. Refrigerate until firm enough to accommodate the stencil. Use a medium-size brush to add the cacao pattern.
Notes
(cake recipe adapted from Sweetapolita, frosting found on Specialty Cake Creations - adapted from the Brown Eyed Baker) Both recipes have been doubled.