Preheat the oven to 350˚F. Lightly spray an 8×8 baking pan with cooking spray.
In a medium skillet, heat the oil on medium heat and fry the spinach for around 2-3 minutes. Remove from heat, and line the bottom of the prepared pan with the spinach, and top with the mozzarella cheese.
In a medium bowl, beat together the eggs and seasoning salt. Pour over the spinach and cheese mixture, and bake for 25 minutes.