Tips: no buttermilk on hand, substitute 2 tsp. vinegar or lemon juice. Mix into 1/2 C. milk. Or use powered buttermilk. Mix according to package directions. In large mixing bowl, combine flour and sugar. In heavy saucepan, combine butter, shortening, coffee or water, and cocoa. Stir and heat to boiling. Pour boiling mixture over flour and sugar in the bowl. Add the buttermilk, eggs, baking soda and vanilla. Mix well, using wooden spoon or high speed on electric mixer. Pour into a well buttered 17 1/2 - by - 11 inch jelly roll pan. Bake 20 minutes or until brownies test done in the center. While brownies bake, prepare frosting. In saucepan, combine butter, cocoa and milk. Heat to boiling, stirring constantly. Mix in the powered sugar and vanilla until frosting is smooth. Pour warm frosting over hot brownies (when brownies come out of oven). Cool and cut into 48 bars.
