One thing that has always stuck out at me with olive oil cakes is the comparisons to a pudding. It brought to mind my family’s Passover seder this year, during which my mother had made a chocolate pudding with a pistachio crumble. It was a delicious combination, and the idea of marrying that chocolatey/nutty/salty profile with the olive oil in this cake seemed too obvious to not try out. A thin layer of chocolate frosting works as the glue for the crunchy topping. —Joshua
Preheat the oven to 350° F. Line the bottom of a 9" round pan with parchment paper.
In one bowl, sift together the flour, sugar, cocoa, espresso powder, salt, baking soda, and baking powder, whisk until combined.
In another bowl, whisk the olive oil, milk, and eggs together.
Add the dry ingredients to the wet, and whisk until combined.
Pour the batter into the pan, and bake for one hour, until a tester comes out clean (save for a little oil - this cake is so moist that a tester won't be entirely clean!). Take out of the oven and let cool about a half hour. Turn it out onto a wire rack and let cool completely.
While the cake is either baking or sitting, prepare the frosting and pistachio crunch. (Note: there will be extra of both, which is not something anyone in my home is complaining about).
For the pistachios, use a sharp knife and a cutting board to chop them to your preferred level of coarseness (using a food processor can too easily result in a powder, and the coarser pieces provide a very welcome crunch). Combine with the flaky salt to taste in a small tupperware. With the lid on, shake to combine.
For the frosting, Melt the butter, and combine with the cocoa powder in the bowl of a stand mixer, or in a regular bowl if using a hand mixer. Stir to combine. Add the powdered sugar, vanilla, and milk, and beat on high speed approximately 2 minutes, until it takes on a light airy texture. Keep in a cool place or in the fridge until ready to use.
Once the cake has cooled, transfer to a plate or platter and add a thin layer of the frosting to the top. Sprinkle the pistachio crunch over the top, and enjoy!