In a heated skillet, add 1 tablespoon of olive oil and diced onions. Add a pinch or two of salt and cook until caramelized. Approximately 15 minutes. Remove from heat and let cool. Set aside 1/4 cup of the onions for topping.
In a large bowl, add ground turkey, mushrooms, panko, Parmesan, dry onion soup mix, minced garlic, remaining olive oil, Worcestershire sauce, and cooled caramelized onions. Fold until incorporated. Shape into 1/4 pound patties. Place on a plate and refrigerate for at least 20 minutes.
Turn Calphalon grill on to 400°F or Preheat oven to 400°F.
Remove burger patties from the refrigerator. Sprinkle patties with salt before grilling or placing them in the oven.
If using the grill, place burger patties on the grill/griddle (you choose) and close—Cook for 5 to 6 minutes. If you’re using the oven, cook for 7 to 8 minutes on each side. When cooking burgers in the oven, you are looking for juices to run clear.
Remove from grill or oven. Top with swiss cheese and remaining cooked onions, serve on your hamburger bun of choice.
Notes
Topping suggestions: sliced tomato, ranch or blue cheese spread. A nice compliment to the burger. Also, you can take the remaining sliced mushrooms and saute. Another great topping to this turkey burger!