Take the banana in a small bowl. Mash it properly using a fork.
Pour the mashed banana into a microwaveable cup.
Add brown sugar along with 1 tbsp. of milk and 1 tbsp. sunflower oil. Mix well with a fork until sugar completely dissolves.
Add Vanilla Essence and mix well.
Add all-purpose flour and ¼ baking soda in a mug.
Add ¼ tsp. Cinnamon powder along with a pinch of salt. Mix all the ingredients well with the banana milk mix. Try to mix gently to avoid any flour lumps.
Add 2 tbsps. Chocolate chunks in the cake batter and mix for a while.
Bake the cake in the microwave for 1 minute.
After a minute, please remove it from the microwave and garnish it with banana slices and pinch of cinnamon powder.
You can have it hot or cold taste will be equally well and delicious.