Pre-heat your OTG at 170 degree C for 10 minute. In a bowl sieve all-purpose flour and cocoa powder.
Add baking soda and sugar. Mix well. In 1 cup of hot water add coffee powder and leave for 30 sec sec.Add vinegar,oil. Add vanilla extract and mix once. Add this liquid solution in 3 batches to dry ingredient.
Stir them until they are combined and form a thin batter. Pour this into 6 inch cake-pan.
Bake for 18 to 20 minute until a skewer comes out clean when pinched at the center. Don’t over bake it.Once it is baked ,leave that for 5 minute inside the oven. Take it out and cool it before you serve.
Dust with powdered vanilla sugar or coconut sugar before serving.It is optional.