Is Potbelly Broccoli Cheddar Soup Vegetarian? While broccoli and cheddar cheese are generally safe for vegetarians, it’s important to consider the full list of ingredients. Many restaurant-style broccoli cheddar soups, including Potbelly’s, often use chicken stock or broth as a base to enhance flavor. According to Potbelly's publicly available ingredient information, their Broccoli Cheddar Soup does contain chicken stock, which means it is not suitable for vegetarians who avoid all meat-based ingredients.