In a large bowl, combine the ground turkey, seasoned bread crumbs, diced onion, chopped parsley, egg, garlic powder, salt, and black pepper.
Gently mix the ingredients with your hands until evenly combined; avoid overworking the meat to keep patties tender.
Divide the mixture into 6 equal portions, roll each into a ball, then flatten each into a patty about 3/4-inch thick.
Heat the olive oil in a large skillet over medium-high heat until shimmering.
Place patties in the hot skillet (do not overcrowd) and cook 2–4 minutes per side, until an instant-read thermometer inserted into the center reads 165°F.
If desired, add cheese to each patty during the last minute of cooking to melt.
Cook remaining patties in batches as needed and transfer cooked patties to a plate to rest briefly before serving.
