I made this dish with chard and enjoyed it just as well. If you decide to use chard instead of spinach, remove the shrimp from the pan after the first 2 minutes of cooking, and set aside on a plate. The chard will take longer to cook, especially if you are using the stems. When the chard is cooked through, add the shrimp back in the pan and continue to cook until the shrimp is just cooked through.
How to make Shrimp Stock Add the shells from 1 lb of shrimp to a medium sauce pan and gently sauté on medium high heat. Once the shells have turned pinkish and no longer translucent, add water into the saucepan to cover the shrimp shells about 2 inches. Add some aromatics to the shrimp and water, such as celery, parsley and a bay leaf, then cook the stock at a simmer for about one hour. Drain the stock through a fine mesh strainer and dispose of the shrimp shells and aromatics. Cool the shrimp stock and refrigerate and use within a couple of days or freeze the stock. The stock should keep well in the freezer for 3 months. Makes about 3 cups of stock.