Preheat oven to 375 °F (190 °C). Spray an 8 1/2"x12" glass or crockery casserole dish with olive oil or nonstick spray.
Heat the oil in a large frying pan, add spinach all at once, and stir just until the spinach is wilted, about 2 minutes.
Transfer spinach to the casserole dish, spreading it around so all the bottom of the dish is covered. Layer the grated cheese and chopped tomatoes and basil on top of the spinach.
Beat the eggs with a little salt and fresh ground pepper to taste. Pour the egg mixture over the spinach/cheese combination, and then use a fork to gently "stir" so the eggs, spinach, and cheese are evenly combined
Bake about 35 minutes or until the mixture is completely set and starting to lightly brown. Let cool about 5 minutes before cutting. Serve hot.
Note: reheat in the microwave for not more than 2 minutes.
There are 103 calories in 1 serving of Spinach & Mozzarella Egg Bake.