Chocolate-Buttermilk Sheet Cake

INGREDIENTS 

2 cups all-purpose flour 

 2 cups sugar   

1 teaspoon baking soda

1/4 teaspoon salt

1 cup butter 

1/3 cup  unsweetened cocoa powder

2 eggs

1/2 cup buttermilk or sour milk

 1 1/2  teaspoons vanilla

1 recipe chocolate-buttermilk frosting

Grease a 15x10x1-inch or 13x9x2-inch baking pan; set aside. In medium bowl  stir together flour, sugar, baking soda, and salt; set aside. In a medium saucepan combine butter, cocoa powder, and 1 cup water. Bring mixture just to boiling, stir constantly. Remove from heat. Add the cocoa mixture to flour mixture and beat with an electric mixer on medium to high speed until thoroughly combined. Add eggs, buttermilk, and vanilla. Beat for one minute (batter will be thin). Pour batter into the prepared pan. Bake in a 350⃝⃝⃝     oven  about 25 minutes for the 15x10-inch pan, 35 minutes for the 13x9x2-inch pan, or until a wooden toothpick comes out clean. Pour warm chocolate-Buttermilk Frosting over the warm cake, spreading evenly. Place cake in pan on a  cool thoroughly.

CHOCOLATE-BUTTERMILK FROSTING

In a medium saucepan combine 1/4 cup butter or margarine, 3 tablespoons unsweetened cocoa powder, and 3 tablespoons buttermilk. Bring to boiling.  Remove from heat. Add 2 1/4 cups sifted powdered sugar and 1/2 teaspoon vanilla . Beat until smooth. If desired, stir in 3/4 cup coarsely chopped pecans.