Preheat the oven to 350°F (175°C).
Lightly grease a 9x13-inch baking dish and place the chicken breasts in a single layer inside the dish.
In a mixing bowl, combine the mayonnaise (or yogurt), grated Parmesan, salt, lemon pepper, and garlic powder until smooth and well blended.
Spread the mayonnaise-Parmesan mixture evenly over the top of each chicken breast.
Optionally sprinkle additional Parmesan over the tops for extra browning.
Bake uncovered for 40–45 minutes, until the chicken is cooked through and juices run clear (internal temperature 165°F / 74°C).