Preheat the oven to 375°F (190°C) and lightly coat a baking dish with non-stick spray.
Pat the chicken breasts dry with paper towels and arrange them in a single layer in the baking dish.
In a small mixing bowl, combine the Caesar dressing, sour cream, grated Parmesan cheese, garlic powder, and black pepper.
Spread the dressing mixture generously over the top of each chicken breast.
Evenly sprinkle the Panko breadcrumbs over the sauce layer.
Bake for 25 to 30 minutes, or until the internal temperature reaches 165°F (74°C) and the topping is golden brown.
Allow the chicken to rest for 5 minutes before garnishing with parsley and serving.