Heat butter in a soup pan or sauce pan. Add in bayleaf and saute for a min.
Add in finely chopped onions and garlic, saute it for couple of mins till it turn translucent.
Add in sliced mushroom and toss well in the butter. As you saute water will leach out, cook on a high heat. the water will evaporate and mushrooms will start getting brown.
Now add in maida and mix well. Saute it for a good 3 mins till the floury taste disappear.
Now add in water and mix well, add in salt and pepper to taste.
Bring it boil, once it starts to boil, let it simmer for 3 mins. Take the bayleaf out.