01 - Preheat the oven to 400°F. Lightly grease a 9x13-inch baking dish with butter or nonstick spray.
02 - Pat the chicken breasts dry with paper towels and arrange them in a single layer in the prepared baking dish.
03 - In a mixing bowl, combine the grated Parmesan cheese, sour cream, minced garlic, melted butter, chopped parsley, dried Italian herbs, salt, black pepper, and red pepper flakes if using. Stir until well blended.
04 - Divide the garlic Parmesan mixture evenly among the chicken breasts, spreading it in a thick layer over the top of each piece.
05 - Sprinkle the panko breadcrumbs evenly over the coated chicken breasts to form a crisp, golden crust.
06 - Bake on the center rack for 25 to 30 minutes, until the chicken reaches an internal temperature of 165°F and the topping is golden brown.
07 - For a crunchier finish, switch the oven to broil and cook for an additional 2 to 3 minutes, watching closely to prevent burning.
08 - Remove the dish from the oven and let the chicken rest for 5 minutes. Garnish with additional chopped parsley and serve immediately.