Preheat oven to 350℉. Spray a 9x13" pan with non-stick cooking spray.
In a large bowl, whisk together flour, sugar, cocoa powder, salt, baking powder and baking soda. Set aside.
In a separate large mixing bowl, whisk together oil, buttermilk, eggs and vanilla.
Pour dry ingredients into the wet ingredient mixing bowl and combine using electric mixer.
Slowly add the hot water while whisking on low speed. Scrape down the sides of the bowl and mix on medium speed for about 1 minute. The batter will be thin.
Pour batter into prepared pan.
Bake for 28-32 minutes until a toothpick comes out clean.
Let it cool completely in pan before frosting. *
Frost with our Chocolate Buttercream Frosting.