Pioneer Woman's Chocolate Sheet Cake

Combine in a mixing bowl:
2 cups flour
2 cups sugar
1/4 teaspoon salt

In a saucepan, melt:
2 sticks butter
Add 4 heaping tablespoons cocoa (I use half dark and half regular).
Stir together.
Add 1 cup boiling water, allow mixture to boil for 30 seconds, then turn off heat. Pour over flour mixture, and stir lightly to cool.

In measuring cup, pour 1/2 cup buttermilk*.
Add:
2 beaten eggs
1 teaspoon baking soda
1 teaspoon vanilla

Stir buttermilk mixture into butter/chocolate mixture. Pour into sheet cake pan and bake at 350-degrees for 20 minutes.

While cake is baking, make icing:
Melt 1 3/4 sticks butter in a saucepan.
Add 4 heaping tablespoons cocoa (I use half dark and half regular), stir to combine, then turn off heat.
Add:
6 tablespoons milk
1 teaspoon vanilla
1 lb minus 1/2 cup powdered sugar
Stir together.
Pour over warm cake.

*If you don't have buttermilk (or don't want to buy an entire container of buttermilk just for this recipe), try this trick: for every ONE CUP of buttermilk you need, take JUST UNDER ONE CUP of milk and add ONE TABLESPOON of either lemon juice or white vinegar. Stir together and let sit for five minutes or so, then use as directed in the recipe.