Combine beef, salt, pepper, onion, bread crumbs, milk and egg. Mix thoroughly and press in bottom and on sides of 9" pie pan to line. Bake in moderate oven (350°F.)35 minutes. Drain off excess fat.
Prepare potatoes as directed on package. (You can cook and mash potatoes if you prefer.) Spread over meat. Sprinkle with cheese. Return to oven and bake until cheese melts, about 10 minutes. Cut in wedges to serve.