When well combine mix in cheese, spinach and onion.
Spread mixture in buttered pan.
Bake 35 min in a 350 degree oven. Let cool 45 min.
I always put my spinach in a pan and cook until thawed and always remember to squeeze all the water out of spinach before mixing it. Regardless whether you put it in a pot or not you have to squeeze the excess water out. I heat it up so I won't freeze my hands.