One of my favorite things to do is come up with new ways to make sandwiches and this was another brainstorm of mine in an effort to do something different. It sounds weird, but it's actually quite tasty, as the sweetness of the grapes goes quite well with the pungent flavor of the cheese. Adjust ingredient amounts to your liking and use any cooked chicken you may have on hand. I love red grapes in chicken salad, so I decided to use that combination in a sandwich. If you're not fond of Gruyere cheese, use any cheese you like! Swiss or fresh mozzarella would work too.