While potatoes are cooking, in large bowl whisk together eggs and egg whites. Add cheese, spinach and salt and pepper. Gently stir in hot potato slices. Wipe out skillet. Add the 2 teaspoons olive oil. Pour in egg/potato mixture, spreading evenly. Cook over medium heat until edges are set, about 15 minutes. Move to oven and bake until set, about 10 to 15 minutes.