Keep the oven for preheating at 180 °C.
Meanwhile in a large mixing bowl add milk, oil, vanilla essence and sugar. Mix everything until sugar dissolves.
Add grated carrot and grated zucchini to the mixture. Stir it.
Take a sifter. Add wheat flour, cinnamon powder, salt, baking powder and baking soda to it. Sift all the dry ingredients.
Mix all the dry ingredients with wet ingredients. Add Vinegar and keep the batter aside for 5 minutes.
Grease a loaf tin with butter and pour the batter into it.
Bake it in a preheated oven at 180 °C for 30 minutes or until it passes the toothpick test.
Once baked, take the tin out from oven.
Let it rest for 5 minutes and then demould it.
Your whole wheat Carrot Zucchini whole cake is ready to serve.