Email to Kelly Boston Market Creamed Spinach Source of Recipe Boston Market List of Ingredients 1 can cream of celery soup 1 T flour 4 T butter 1 small onion, chopped 2 - 10 oz boxes frozen spinach, cooked & drained black pepper/salt/garlic powder Instructions In saucepan, over medium heat, combine soup, flour, S&P, and garlic powder until smooth and hot. Add spinach and onion.