01 - Preheat oven to 400°F. Lightly grease a 9x13-inch baking dish with cooking spray or a small amount of oil.
02 - Pat chicken breasts dry with paper towels. Season both sides generously with salt and black pepper. Arrange seasoned chicken in the prepared baking dish in a single layer.
03 - In a medium bowl, combine Caesar dressing, sour cream (or Greek yogurt), grated Parmesan, minced garlic, Dijon mustard, and lemon juice. Whisk vigorously until completely smooth and well incorporated.
04 - Spread the creamy Caesar sauce evenly over each chicken breast, using a spoon or spatula to ensure complete coverage on all exposed surfaces.
05 - Sprinkle shredded mozzarella cheese and additional grated Parmesan evenly over the sauced chicken breasts.
06 - Bake uncovered for 25-30 minutes, or until chicken reaches an internal temperature of 165°F and the cheese topping is golden brown and bubbling.
07 - Remove from oven and let chicken rest for 5 minutes to allow juices to redistribute. Garnish with fresh chopped parsley before serving.