Chocolate Sheet Cake
["1 stick butter", "1/2 cup oil", "4 tablespoons cocoa", "1 cup water", "2 cups flour", "2 cups sugar", "1/2 cup buttermilk", "2 eggs", "1 teaspoon baking soda", "1 teaspoon vanilla"]
["In saucepan bring to a boil butter, oil, cocoa, and water. Sift together flour and sugar. Pour chocolate sauce over dry ingredients and mix well. Add buttermilk, eggs, baking soda, and vanilla. Pour into a greased cookie sheet. Bake at 400\u00b0 for 20 minutes."]
["butter", "oil", "cocoa", "water", "flour", "sugar", "buttermilk", "eggs", "baking soda", "vanilla"]