Preheat oven to 350.
Add diced onion, ground beef, Worcestershire sauce and salt and pepper to skillet.
Cook until ground beef is nearly done.
Add drained vegetables and continue cooking until meat is fully browned.
Add beef/vegetable mixture to lightly greased baking dish.
Top with mashed potatoes.
Sprinkle cheese on top.
Bake 20 - 30 minutes or until cheese is lightly browned.
Remove from heat and let stand 5 minutes.
Serve and enjoy!