Cook the spinach. If you're using fresh, put about 1/2 cup of water and the spinach in a pan. Bring to a boil and then turn down the heat. Simmer for a few minutes, covered, stirring now and then until the spinach is wilted and cooked. If you're using frozen, follow the directions. Drain the spinach well, whether you used fresh or frozen.
Cream of Celery Soup
Make a cream of celery soup. If you're in a hurry, just skip this step and warm up a can of store-bought.
Melt the 3 Tbs butter in a saucepan over medium low heat and sautee the celery and onion in the butter until soft.
Stir in the flour and salt and cook for 2 minutes, stirring constantly.
Using a wire whisk, slowly add the milk or broth and cook until smooth and thick. (If you heat the milk or broth first, it is easier to avoid lumps.)
To the soup, add the additional butter or oil, garlic salt, salt and pepper and stir with a whisk until smooth.
Combine with the cooked spinach and heat through.