The BEST Chocolate Sheet Cake

INGREDIENTS
For the Cake:

• 2 cups all-purpose flour
• 2 cups sugar
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 1/2 cup buttermilk
• 2 eggs
• 2 teaspoons vanilla extract
• 1/2 cup cocoa powder
• 1 cup water or black coffee
• 2 sticks butter (real, salted)

For the Icing:

• 1 1-lb box powdered sugar
• 1 1/2 sticks butter (real, salted)
• 1/2 cup cocoa powder
• 1/2 cup milk
• Dash of salt
• 1 teaspoon vanilla extract

INSTRUCTIONS

1. Grease a 10x15 baking pan (or spray with cooking spray) and preheat oven to 350 degrees. See notes below regarding other pan sizes.
2. Combine flour, sugar, baking soda and salt in a large mixing bowl. Whisk to incorporate ingredients then set aside.
3. Combine buttermilk, eggs and vanilla extract in a small bowl then mix well and set aside.
4. Add cocoa powder to a small saucepan then whisk in water or black coffee until smooth. Add butter then stir and heat over medium-high heat until boiling. Remove from heat.
5. Pour hot cocoa power mixture into bowl with flour mixture then stir to incorporate.