In a large mixing bowl, combine the ground turkey, breadcrumbs, Parmesan cheese, chopped onion, minced garlic, Worcestershire sauce, oregano, salt, black pepper, and red pepper flakes (if using). Mix until just combined; avoid overmixing to keep the burgers tender.

Divide the mixture into four equal portions and shape each portion into a patty about 3/4 inch thick. Make a slight indentation in the center of each patty to prevent them from puffing up while cooking.

Heat the olive oil in a large skillet over medium heat. Once hot, add the patties and cook for about 5-6 minutes on each side, or until the internal temperature reaches 165°F and the burgers are golden brown.

While the burgers are cooking, toast the whole wheat buns in a toaster or on a separate skillet until lightly browned.

Assemble the burgers by placing each patty on a bun and topping with lettuce, tomato, and your favorite condiments. Serve immediately.