1 lb. ground beef (browned and drained)
1/2 lb. American cheese (chopped in sm. pieces)
1/2 sm. onion
2 (6 oz.) cans tomato paste
1 tsp. oregano
Grated Parmesan cheese or Romano

Mix thoroughly while hamburger is still warm. Spread on buns; sprinkle with Parmesan cheese. Place under broiler until golden brown. Serve hot. Makes 1 dozen buns (24 halves).