Here we'll hedge a little and answer yes and no. While traditional Chicken Florentine uses these cheeses, you are perfectly welcome to use the cheese of your choice. Gruyère cheese is a traditional Swiss cheese with a mild and a sweet flavor but mildly salty. Parmesan cheese is added from skimmed milk and is a substitute for the more expensive Gruyère cheese. You are certainly welcome to substitute other cheeses as you wish, however, we cannot vouch for the flavor. As Chief Dan George mimicked in the classic 1970 movie, Little Big Man, - Sometimes the magic works, and sometimes it doesn't. -