Preheat the oven to 350°F. Grease and flour three 6-inch cake pans and set aside.
Sift together the flour, cocoa power, baking powder, baking soda, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the oil and sugar on medium speed for 2 minutes. Add the vanilla and eggs, one at a time. Stop the mixer and scrape down the bowl.
Turn the mixer to low and add the flour mixture in three batches, alternating with the milk, beginning and ending with the flour mixture. Stop and scrape down the bowl. With the mixer on low, stream in the coffee. Mix on medium-low for no more than 30 seconds, or until the batter is combined.
Evenly divide the batter among the prepared pans. Bake for 25 to 28 minutes, or until a toothpick inserted into the center of the cakes comes out clean. Let them cool on a wire rack for 10 to 15 minutes before removing the cakes from their pans.