Preheat oven to 350 degrees
Over medium high heat, add a non stick pan. Add your onion, mushroom, garlic and salt
Saute until no water remains. It should completely dry out. About 8 minutes.
Add your spinach to the pan and cook for about 2 minutes
Spray a 9 inch pie dish with non stick cooking spray.
Add in your mushroom mixture and spread out evenly. Top with your sliced mozzarella.
In a bowl, whisk together your 4 eggs. Add your parmesan and mix together.
Pour your eggs over the mushroom mixture.
Bake for 30 minutes or until set