Preheat the oven to 180 C / Gas mark 4. Grease and flour two 23cm (9 in) round cake tins.
In large bowl combine flour, sugar, cocoa, bicarbonate of soda, baking powder and salt. Make a well in the centre.
Add eggs, coffee, buttermilk, oil and vanilla. Beat for 2 minutes on medium speed. Batter will be thin. Pour into prepared tins.
Bake in preheated oven for 30 to 40 minutes, or until a skewer inserted into centre of cake comes out clean. Cool for 10 minutes, then remove from tins and finish cooling on a wire rack. Fill and ice as desired.