Step 1

In a saucepan mix cola, oil, butter and cocoa and bring to boil. In bowl combine sugar, flour and salt. Pour the Cola mixture over the flour mixture and beat well.

Step 2

Add eggs, buttermilk, baking soda and vanilla and beat well. Pour mixture into a greased and floured 13x9 inch baking pan. Bake at 350 degrees for 20 to 25 minutes.

Step 3

Frosting:In a saucepan, combine butter, cocoa, and milk. Heat until butter melts. Beat in remaining ingredients and spread on cake while still warm.