This recipe can be halved for a single layer. But if you have a small oven or one pan, don't leave the batter lying around. It won't give the desired result. Just bake half the recipe twice.
The whole recipe can be baked in 8 or 9 inch square pan for 40 to 50 minutes at 160 C/ 325 F.
You can use apple cider or regular vinegar.
You can use cool coffee instead of the water or substitute ¼ cup of it for some rum.
My measuring cup measures 240 ml.