Sauté onions in butter until soft. Layer half of onions in 1 ½ qt. casserole or 9X12 dish. Sprinkle with Parmesan. ½ Ritz crackers and ½ cheese crackers, salt and pepper. Repeat for second layer.
Spread celery soup on top.
Cover with cheddar and a little more Parmesan cheese.
Add paprika for color.
Bake at 350 for 30 minutes