1. Preheat oven to 350° F.
2. Place chicken breast in an oiled 8" x 8" baking pan.
3. Arrange mushrooms and onion around the chicken breast.
4. Sprinkle with garlic, black pepper, and garlic powder.
5. Bake for 25 minutes, then turn over and cook for an additional 25 minutes, or until done.
6. Place cooked chicken on cooked rice, and then sprinkle with parsley to serve!