Preheat your oven to 180°C/350°F and grease and flour 2 6-inch round cake pans and line the bottoms with parchment.
Whisk together the flour, cocoa powder, baking powder, baking soda and salt.
In a separate bowl, whisk together the water, sugar, oil, vinegar, vanilla and coffee.
Add the wet ingredients to the dry and whisk until smooth.
Divide evenly between the two pans and bake for 35-40 minutes or until a toothpick inserted in the center comes out clean.
Let them cool almost completely before removing them from the pans because they’ll be quite fragile. Then let them cool on a wire rack.