Preparation of Oven: First, set the oven to preheat at a temperature of 375°F (190°C).

Arrangement of Chicken: In a suitable baking dish, methodically arrange the boneless chicken breast halves, ensuring they are evenly spaced and not overlapping.

Preparation of Mixture: In a separate, clean mixing bowl, thoroughly combine the mayonnaise, Parmesan cheese, salt, ground black pepper, and garlic powder until they form a consistent mixture.

Application of Mixture: Using a spatula or the back of a spoon, evenly coat the chicken breast halves with the previously prepared mayonnaise and Parmesan mixture.

Baking: Position the baking dish in the preheated oven and allow the chicken to bake for approximately 45 minutes. It is crucial to ensure that the chicken is thoroughly cooked and the topping has acquired a golden-brown hue. Confirm the chicken's doneness by using a meat thermometer; the internal temperature should register at 165°F (74°C).