In a small bowl, beat the egg and egg whites. Add cheeses, salt, pepper flakes, garlic powder and pepper; mix well. Set aside. In an 8-in. nonstick skillet, sauté the mushrooms, green pepper and onion in oil for 4-5 minutes or until tender. Add chicken sausage; cook and stir until chicken is warm. Add egg mixture. As eggs set, lift edges, letting uncooked portion flow underneath. Cut into wedges. Serve immediately.