Some spinach soup recipes include a basic one from Ree Drummond, combining the spinach with garlic, onion, milk and seasonings, and Martha Stewart's more complex recipe for Spinach Cream Soup, which is served with home-made croutons. Another recipe from Real Simple combines spinach with potato and broccoli.
To make Ree Drummond's simple spinach soup, cook olive oil and garlic in a skillet with olive oil, then puree in a food processor with hot water. Heat onions and butter in a soup pot, adding flour, then milk, followed by salt, cayenne and black pepper. Add the spinach puree and continue to cook until thick.
To make Martha Stewart's Spinach Cream Soup, saute onions, then add flour and chicken stock to simmer. Blanch the spinach in boiling water then cool immediately in icy water. Puree the stock and onion mixture with the spinach in a food processor and pass through a sieve into a cooking pot. Over a low heat, whisk cream into the soup. To make the croutons, fry cubes of French bread in extra-virgin olive oil.
To make Real Simple's Creamy Broccoli and Spinach Soup, soften leeks in butter with salt and pepper, then add vegetable broth, broccoli and potato. Stir in spinach until it has wilted, then puree in a food processor. Serve topped with sour cream and black pepper.