1. Preheat your oven to 450 degrees F.
2. Pat dry a thawed raw chicken with paper towels and place into a greased 9x13 baking dish.
3. In a bowl, mix together the butter, 2 Tbsp of fresh chopped rosemary, 1 tsp of salt, 1/2 tsp black pepper, 1/2 tsp garlic powder and 1/2 tsp onion powder until blended.
4. Rub the chicken with the butter mixture and get some under the chicken on the breasts too.
5. Inside the chickens cavity, place a quarter of an onion, 2 carrots sliced down the middle and in half length wise and halved celery stalks. Try to pack them in there as best as you can, but it's okay if it doesn't all fit.
6. Wash your baby carrots and your potatoes. Quarter the potatoes or cut them into 1 inch sized cubes (whichever is smaller).
7. In a large glass bowl or gallon sized-ziploc bag, mix the carrots, potatoes, and remaining seasonings as well as 3 Tbsp of olive oil.
8. Place the potato and carrot mixture around the chicken in the pan.
9. Bake in the oven for 30 minutes and then reduce the heat to 375 degrees F for 40-50 minutes or until the chicken registers 160-165 degrees F.