cups shredded cheddar cheese, DIVIDED (or shredded American cheese, divided)
Prepare pasta according ton package directions; drain. Do NOT rinse.
While pasta is cooking, in a large skillet, brown ground beef with onion. Drain fat.
Return beef and onion mixture to hot skillet. Over low-med heat, stir in tomatoes, tomato sauce, milk, mayo, ketchup, relish, mustard, pepper, salt, garlic powder, oregano and 2 1/2 cups cheese. Stir and cook until cheese is melted. Add hot cooked pasta and gently mix together.
At this point either:
a) sprinkle with remaining 1/2 cup cheese; heat through and serve. OR.
b) Pour into a 13" x 9" or larger baking dish, sprinkle with remaining 1/2 cup cheese ans bake at 350 for 20-25 minutes.