1 lb. ground beef
1 onion, chopped
1/2 c. ketchup
2 tsp. Parmesan cheese
1/2 c. tomato sauce
1/4 tsp. garlic powder
1/4 tsp. butter
1/4 tsp. oregano
Sliced Mozzarella cheese

Brown ground beef. Add all other ingredients except Mozzarella cheese. Simmer for 20 minutes. Spoon on hamburger buns. Put a slice of Mozzarella cheese on top of ground beef and seal in foil. Bake in oven at 350 degrees for 15 minutes.