Preheat oven to 400 degrees F.
Line a 13x9x2-inch baking pan with aluminum foil. Spray with non-stick cooking spray (coat well).
Combine hot cooked spaghetti with butter; stir until butter melts and coats spaghetti.
Add ½ cup Parmesan cheese; stir to coat. Arrange spaghetti in an even layer in foil-lined pan.
Spread ricotta cheese over spaghetti. Sprinkle with ¼ cup Parmesan cheese.
Brown ground beef, drain; add pasta sauce and heat until bubbly. Spoon over cheeses.
Top with mozzarella cheese and remaining Parmesan cheese.
Cover with foil. Bake 30 minutes.
Remove foil cover and continue baking 15 minutes or until cheese is lightly browned. Let stand 10 minutes before serving. Serve with tossed salad and warm Italian bread.