Mix Parmesan cheese, mayonnaise, and garlic powder together in a bowl.
Arrange chicken breasts in a 9x13-inch baking dish; top with artichoke hearts and crimini mushrooms. Spread cheese mixture over the artichoke and mushroom layer.
Bake in the preheated oven until the chicken no longer pink in the center and the juices run clear, about 30 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
