Step 1

Combine turkey carcass, halved onion, roughly chopped carrot, roughly chopped celery, halved garlic head, 1 teaspoon rosemary, thyme, bay leaves, salt, and pepper in a stockpot; pour in enough water to cover. Bring mixture to a boil, cover pot, reduce heat, and simmer until flavors have blended, about 1 hour.

Step 2

Remove turkey carcass and pull remaining meat from bones; reserve meat and discard carcass. Remove vegetables and bay leaves from stock using a slotted spoon and discard.

Step 3

Stir diced onions, diced carrots, diced celery, minced garlic, poultry seasoning, 1 teaspoon rosemary, and onion powder into stock; bring to a boil. Reduce heat, cover pot, and simmer until vegetables are very tender, 20 to 30 minutes. Add cooked rice and turkey meat to soup; season with salt and pepper. Cook until rice and turkey meat are warmed, about 5 minutes.