Preheat oven to 375°F. Spray 9-inch pie plate with nonstick cooking spray.
Cook orzo according to package directions, omitting any salt. Drain.
Whisk milk, egg whites, salt, if desired, nutmeg, and pepper in large bowl until well blended. Stir in spinach and 2 tablespoons cheese. Add orzo; gently mix. Spoon evenly into prepared pie plate.
Combine bread crumbs and remaining 2 tablespoons cheese in small bowl. Stir in butter. Sprinkle evenly over spinach mixture.
Bake 20 minutes or until topping is golden brown and center is set. Let stand 5 minutes before serving.
Serving Size 4 servings
Servings 14
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.