Wash the mushrooms, onions and spinach. Cut them finely. Put the butter in a pot. Saute the onions in it and then the spinach.
Finally, put in the mushrooms as well. Pour in 4 cups of water and leave the dish to simmer. Once the suillus mushrooms soften, pour in the milk.
Stir and season it to taste. Remove from the stove after 6-8 min.