Clean mushrooms ,quickly rinse and chop it finely.
In the same pan , heat butter .Add finely chopped onions and garlic. Saute for 2-3 mins.
When onions turn translucent, add chopped mushroom and saute for a few minutes. Let the water released from mushroom dry.
Add maida to the mushrooms and saute for 2-3 mins . Add a cup of water and cook till mushroom is done.
Take half the quantity of mushroom in a blender and puree smooth .
Add mushroom puree to the remaining mushroom slices and add milk. Add salt and mix well. Now add some water to adjust the soup to the desired consistency.
On a low flame let the soup come to boil.Stir in between.We can see that the soup has thickened .
Lastly sprinkle freshly ground pepper powder and some oregano powder. Stir and just bring to a boil.Switch off.
Serve hot steaming cream of mushroom soup garnished with coriander leaves / parsely/spring onions /grated cheese
Notes
Instead of maida you can also use cornflour.
In the above i've used oregano powder for flavoring. Instead of that you can use dried basil or thyme or any other indian spices or omit all and keep it simple.If you wish you can increase the quantity of mushrooms.
If you want you can add choice of finely chopped veggies too.