Preheat oven to 375°F.
Cook potatoes in boiling water
until tender.
In a nonstick pan, add vegetable
spray and warm over medium heat.
Add onion and sauté until brown.
Add vegetables and sauté until tender but not brown.
In a medium mixing bowl, slightly
beat eggs and egg whites, pepper, garlic salt, and low-fat mozzarella cheese. Stir
egg-cheese mixture into the cooked vegetables.
In a 10-inch pie pan or ovenproof
skillet, add vegetable spray and transfer potatoes and egg mixture to pan. Sprinkle
with
low-fat Parmesan cheese and bake until firm and brown on top, about 20 to 30
minutes.
Remove omelet from oven, cool for
10 minutes, and cut into 5 pieces.