Hearty Chicken and Wild Rice Soup

chicken thighs, bone-in, skin-on (you can also use breast meat but for the most flavor the more dark meat you cook the better)

kosher salt

black pepper

sprigs fresh rosemary (or about 1 teaspoon dried)

olive oil

onion, diced

carrots, diced

celery diced

mushrooms, coarsely chopped

cooked wild or brown rice (see note)