Preheat oven to 350 degrees F.
In a medium mixing bowl, combine softened cream cheese, onion powder, garlic powder and salt and mix well. Stir in spinach.
Stuff filling into the mushrooms, about 1 teaspoon of filling give or take depending the size of the mushroom, and place in a baking dish
Bake at 350 degrees F for 15 to 20 minutes until the mushrooms are soft.
I garnished the top with additional parmesan cheese for the picture. This is completely optional.
