Chocolate Sheet Cake

• Cake

• 2 cups all-purpose flour
• 2 cups sugar
• 1 tsp baking soda
• 1/2 tsp salt
• 1 cup butter
• 1/4 cup unsweetened cocoa powder
• 1 cup water
• 1/2 cup buttermilk (or milk mixed with 1 1/2 tsp vinegar)
• 2 large eggs
• 1 tsp vanilla extract

• Frosting

• 1/2 cup butter
• 1/4 cup unsweetened cocoa powder
• 1/3 cup milk
• 3 1/2 cups powdered sugar
• 1 tsp vanilla extract

1. Cake
2. 1Heat the oven to 350°F and grease a 13x18-inch rimmed baking sheet (or a 9x13-inch pan; bake it 30–35 minutes).
3. 2Whisk the flour, sugar, baking soda and salt in a large bowl.
4. 3In a saucepan, bring the butter, cocoa and water to a boil, stirring. Pour it over the flour mixture and stir until smooth.
5. 4Whisk in the buttermilk, eggs and vanilla. Pour into the pan.
6. 5Bake 20–25 minutes, until a toothpick in the center comes out clean.
7. Frosting
8. 6In the last 5 minutes of baking, melt the butter with the cocoa and milk in a saucepan. Take it off the heat and whisk in the powdered sugar and vanilla until smooth.
9. 7Pour the warm frosting over the warm cake and spread it to the edges. Let it set for 30 minutes before cutting.

Tap a step to mark it done.