1. Melt the butter in a heavy saucepan.
2. Add the finely chopped onions and garlic.
3. Saute till the onions soften and become translucent.
4. Add the sliced or chopped mushrooms and saute till the mushrooms start to release water.
5. Saute till all the water dries up and the mushrooms become a light golden.
6. Add the oats and saute for 3 to 4 minutes stirring often on a low to medium-low flame. the raw aroma of oats should go away. now add water and boil it for sometime..
7. Let broth of mushrooms come to room temperature. now blend it till it become smooth.
8. On a low to medium-low flame let the soup come to gentle simmer first.
9. Then add milk and freshly crushed black pepper, mix herbs and mix well.
10. Stir well and season with salt.
11. The mushroom soup would also begin to thicken. stir at intervals.
12. Then add the cream and chopped parsley.
13. Simmer mushroom soup for 1 to 2 minutes and keep stirring.
14. Switch off the flame and pour the soup in individual serving bowls.
15. Serve the cream of mushroom soup steaming hot garnished with parsley or coriander.