Preheat oven to 350°F. Grease 9x13-inch pan. Mix butter, sugars, eggs, buttermilk and vanilla, then add cocoa, flour, salt, and baking soda. ... 30 minutes then frost. Place all ingredients except ... will cause the frosting to be "sugary" or grainy.
Ingredients: 15 (buttermilk .. cocoa .. cream .. eggs .. flour .. salt ...)