• Preheat oven to 375 degrees F. Butter and flour a half-sheet pan (18x12) or jelly roll pan (15x10).
• Sift flour and salt into large bowl. Add sugar and whisk until blended.

  2 cups all-purpose flour, 1/8 teaspoon salt, 2 cups granulated sugar
• Combine butter, cocoa, and water in a saucepan. Bring to a boil and pour over the flour and sugar. Whisk until blended.

  2 sticks unsalted butter, ¼ cup cocoa, 1 cup water
• Add the baking soda, buttermilk, eggs, and vanilla. Whisk until blended and smooth. Pour into greased and floured baking pan.

  1 teaspoon baking soda, ½ cup buttermilk, 2 large eggs, 1 teaspoon vanilla
• Bake for 12-20 minutes, checking cake after 12. Cake is done when tester comes out clean but be careful not to overcook.

Frosting

• While cake is baking, bring the butter, milk, cocoa, and salt to a boil in a saucepan and pour over the powdered sugar. Add vanilla and pecans (if using). Mix well and immediately spread on warm cake.

  12 tablespoons unsalted butter, 6 tablespoons whole milk, ¼ cup cocoa, pinch of salt, 3 3/4 cups powdered sugar, sifted, 1 teaspoon vanilla, 1 cup chopped toasted pecans, (optional)