In large bowl, stir together sugar, flour, cocoa, baking soda, baking powder and salt.
Add eggs, buttermilk, coffee (if making with instant, use 2 tsp to make 1 cup), oil and vanilla; beat on medium speed of electric mixer 2 minutes. Batter will be thin.
Pour into prepared pan.
Bake until cake tester inserted in centre comes out clean (30-35 minutes for round pans, 35-40 minutes for rectangular pans).
Cool 10 minutes; (if using 9-inch round cake pans, remove from pan) and cool on wire racks.
Cool completely, then frost with your favourite vanilla icing.