1. Need a 17 1/2-inch x 11-inch jelly roll pan.
2. First, if you do not have buttermilk on hand, you can substitute 2 t. vinegar or lemon juice and mix with 1/2 c. milk. You can also use powdered buttermilk. Just mix according to the package directions.
3. In a large mixing bowl, combine the flour and sugar.
4. In a heavy saucepan, combine butter, shortening, coffee or water and cocoa. Stir and heat to boiling.
5. Pour boiling mixture over the flour and sugar in the bowl. Add the buttermilk, eggs, baking soda and vanilla.
6. Mix well, using a wooden spoon or high speed on an electric mixer.
7. Pour into a well buttered 17 1/2-inch by 11-inch jelly roll pan.
8. Bake at 400 degrees F. for 20 minutes or until the brownies test done in the center.
9. While brownies bake, prepare the frosting. In a saucepan, combine the butter, cocoa and milk. Heat to boiling, stirring. It will look like it is seperating when it starts boiling.
10. Mix in the powdered sugar and vanilla until frosting is smooth.
11. Pour warm frosting over the brownies as soon as you take them out of the oven. Cool. Cut into bars. Oh baby, oh Baby!!!