Put the water, margarine, seasoning packet, milk, and half of the soup in a pan.
Mix well and heat on the stove, stirring until the mixture comes to a boil.
In a bowl, combine the stuffing mix, eggs, mushrooms, and the remaining soup.
Add the hot mixture and mix well.
Transfer to a greased 2-quart casserole dish.
Cover and bake at 350 degrees for 40–45 minutes.