1. Preheat oven to 400°F. Lightly grease a baking tray / sheet with cooking oil spray, or a light coating of oil. Set aside.
2. Combine together the butter, broth, garlic, parsley, thyme and rosemary together in a bowl.
3. Place chicken on the baking sheet and arrange the potatoes all around the chicken. Toss 1/2 cup of sauce through the chicken and potatoes, and season well with salt and pepper. Lightly spray all over with olive oil spray or cooking oil spray.
4. Bake in preheated oven for 15 minutes or when potatoes just start to become golden.
5. Carefully remove baking tray from the oven and flip each chicken breast. Move the potatoes to one side and place the green beans around the chicken on the other side of the baking sheet. Pour the remaining garlic herb butter sauce over the beans, toss well and return to the oven for a further 10 minutes, or until chicken is cooked through (no longer pink in the middle) and potatoes are for tender.
6. Broil (or grill) for 2-3 minutes until chicken is golden and potatoes crisp.
7. Sprinkle with fresh chopped herbs (optional), and serve immediately with pan juices.