Yes it is the large portabella mushrooms. Publix has them pre-sliced
packaged and that is what that recipe is calling for. Remember, this is from Apron's so they use time savers all over the place for customers. They usually try to time there meals around a 30 minute time frame. I always buy the whole ones and cut them myself. I really think you'll like these Marilyn. Let me know if you make them.