I got this recipe from one of the tear off pads at a Penzeys store a couple of years ago. I use an Italian cheese blend instead of swiss. I also use turkey ham. It takes a little time to assemble but is well worth it.
Found this recipe last year when blueberries just came into season. We had them a few times and love them. You can't taste the blueberries too much but the burgers are really moist and flavorful. You can also use frozen blueberries but need to thaw them out before using.