Preheat oven to 350 degrees. Mix all the dry ingredients. Blend in the coffee, mayonnaise and vanilla. Grease and flour an 20 cm round cake pan. Pour in the batter and bake in preheated oven for 45 minutes. Test to see if it's done by inserting a knife in the middle. If it comes out clean, that means the cake is done. Remove from oven and cool on a wire rack. Slice and serve.