01 - Preheat oven to 400°F. Lightly grease a 9x13-inch baking dish with cooking spray or butter.
02 - Pat chicken breasts dry with paper towels. Season both sides with salt and black pepper. Arrange in the prepared baking dish.
03 - In a medium bowl, combine Caesar dressing, sour cream (or Greek yogurt), grated Parmesan, minced garlic, Dijon mustard, and lemon juice. Mix until smooth and well incorporated.
04 - Spread the sauce evenly over the chicken breasts, ensuring they are fully coated on all sides.
05 - Sprinkle mozzarella and additional Parmesan cheese over the top of the sauced chicken.
06 - Bake uncovered for 25-30 minutes, or until chicken is cooked through (internal temperature reaches 165°F) and the top is golden and bubbling.
07 - Let rest for 5 minutes before serving. Garnish with fresh parsley if desired.