Heat the oven to 375°F. Spray a 2-quart shallow baking dish with the cooking spray.
Beat the eggs in a large bowl with a fork or whisk. Stir in the soup. Stir in the spinach, 1 cup cheese and black pepper. Pour the egg mixture into the baking dish.
Bake for 35 minutes or until set. Sprinkle with the remaining cheese.
Tip: You can prepare the frittata as directed above then cover and refrigerate for up to 24 hours. Before serving, remove the frittata from the refrigerator and let stand for about 30 minutes. Heat the oven to 350°F. Bake for 20 minutes or until hot.