Combine the all-purpose flour, sugar, cocoa powder, espresso powder, baking soda, baking powder, and salt in a large mixing basin or the bowl of a stand-up mixer (with the paddle attachment). Mix until everything is well blended. After that, add the egg and egg yolk, buttermilk, warm water, olive oil, and vanilla extract. 1 minute of mixing until the batter is smooth and well blended. It's okay if the batter is thinner than you're used to with cake batter.