01 - Preheat oven to 400°F. Lightly grease a 9x13-inch baking dish.
02 - Pat chicken breasts dry and evenly season both sides with salt, black pepper, and garlic powder. Arrange chicken in the prepared baking dish.
03 - In a medium saucepan over medium heat, warm olive oil. Add minced garlic and sauté until fragrant, approximately 1 minute.
04 - Add heavy cream, chicken broth, 0.5 cup Parmesan, lemon zest and juice, Dijon mustard, and dried Italian herbs. Simmer while stirring frequently for 2–3 minutes.
05 - For a thicker consistency, whisk flour with 2 tablespoons water to form a slurry. Stir slurry into sauce and cook 1–2 minutes more until thickened.
06 - Pour the creamy sauce evenly over chicken breasts. Sprinkle remaining 0.25 cup Parmesan cheese over the top.
07 - Bake uncovered for 30–35 minutes until chicken reaches an internal temperature of 165°F and the crust is lightly golden.
08 - Garnish hot chicken with chopped fresh parsley before serving.