Preheat oven to 350 degrees F. Grease and flour two 9 inch round cake pans or one 9x13 inch pan.
In large bowl combine flour, sugar, cocoa, baking soda, baking powder and salt. Make a well in the center.
Add eggs, coffee, buttermilk, oil and vanilla. Beat for 2 minutes on medium speed. Batter will be thin. Pour into prepared pans.
Bake at 350 degrees F for 30 to 40 minutes, or until toothpick inserted into center of cake comes out clean. Cool for 10 minutes, then remove from pans and finish cooling on a wire rack. Fill and frost as desired.