One Pot Chicken, Rice and Vegetables

chicken thighs (preferably with skin and bones but boneless and skinless will also work)

salt

black pepper

TB butter (or olive oil, divided)

large carrots (diced (about 1 cup))

celery stalks (diced (about 1 cup))

white onion (diced (about 1/2 cup))

garlic cloves (minced)

white rice (or brown rice, I like white jasmine rice)

broth (Vegetable or chicken broth work great. Water may also be used as a substitute)

sprigs fresh thyme

frozen peas