Broccoli Souffle

2 packages frozen chopped broccoli
1 can cream of celery soup (undiluted)
1 cup mayonnaise
3 tablespoons grated onion
2 eggs, beaten
1 cup grated cheddar cheese
1 sleeve Ritz crackers, crushed
1 stick melted margarine or butter

Cook broccoli; drain and cool. Mix soup, mayonnaise, onion, egg, and cheese and add to cooled broccoli. Lightly grease 3 1/2-quart crock pot and add mixture. Mix 1 sleeve Ritz crackers with melted margarine or butter. Sprinkle on top. Cook on high for 2 to 3 hours.