Preheat oven to 450°F. Heat large nonstick skillet over medium heat until hot. Add Ground Beef and onion; cook 8 to 10 minutes, breaking into 3/4-inch crumbles and stirring occasionally. Remove from skillet with slotted spoon; pour off drippings. Return beef to skillet; stir in gravy and peas and season with pepper.
Spoon beef mixture into 2-quart baking dish. Top with potatoes, spreading evenly; sprinkle with cheese, if desired. Bake in 450°F oven 25 to 30 minutes or until bubbly and cheese begins to brown.
Nutrition information per serving: 389 Calories; 9 kcal Calories from fat; 1 g Total Fat; 4 g Saturated Fat; 4 g Monounsaturated Fat; 85 mg Cholesterol; 1054 mg Sodium; 4 g Total Carbohydrate; 2.7 g Dietary Fiber; 35 g Protein; 4.4 mg Iron; 8.9 mg Niacin; 0.8 mg Vitamin B6; 2.4 mcg Vitamin B12; 7.1 mg Zinc; 20.4 mcg Selenium;