Preheat oven to 350°F and grease a 9x13" pan with cooking spray.
In a large mixing bowl or bowl of a stand mixer, add the flour, sugar, cocoa powder, salt, baking powder and baking soda; stir to combine.
2 cups all-purpose flour, 2 cups sugar, 3/4 cup cocoa powder, 1 teaspoon salt, 1 teaspoon baking powder, 2 teaspoons baking soda
In a separate bowl, whisk together the oil, buttermilk, eggs and vanilla.
1/2 cup vegetable oil, 1 cup buttermilk, 2 eggs, 1 teaspoon vanilla
Pour the wet ingredients into the mixing bowl with the dry ingredients.
Stir until well-mixed, scraping down the sides of the bowl a time or two.
Slowly add the coffee and mix until combined.
1 cup hot coffee
Pour the batter into the prepared pan.
Bake for 28-32 minutes, or until a toothpick comes out clean (or with a few moist crumbs).
Let cool completely before frosting.