Preheat oven to 350 degrees (F). Spray a 9×13 pan with non-stick spray and line with parchment paper or foil for easy removal once cooled.
In a large bowl whisk the flour, cocoa powder, espresso powder, salt baking soda, and baking powder until well combined and free of lumps. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or in a large bowl with a hand mixer beat the sugar and vegetable oil until light and fluffy.
Add the eggs one at a time, mixing well and scraping down the sides of the bowl between each addition. Add the vanilla and combine.
Slowly add the milk to the sugar mixture, alternating with the dry ingredients.
Mix until just combined. Scrape down the sides of the bowl to ensure it is fully combined. The batter will be thin.
Pour the batter into the prepared pan. Bake the cake for 30-35 minutes or until a toothpick inserted in the center of the cake comes out with only a few moist crumbs.
Remove the cake from the oven and allow the cake to cool before frosting.