Heat oil in a thick bottomed pan , add onion, minced garlic and celery, cook for 2-3 minutes until it is softened a bit.
Add bay leaf, chopped cauliflower, 1 cup water, one cup of milk, salt, pepper.
Cover the saucepan and let the contents simmer for 8-9 minutes , until cauliflower is soft which will take from 7-8 minutes.
While the pot is simmering in a bowl whisk potato flakes/flour in remaining half cup of milk.
Add this milk mixture to the simmering pot after 8 minutes , cook it over slow heat and continue stirring the soup for 2-3 minutes and remove from heat.
Finally add cheese and season it according to taste and serve hot.