Homemade Chicken Noodle Soup

Name: Homemade Chicken Noodle Soup
Ingredients: 1 large yellow onion; 3 medium carrots; 3 medium stalks celery; 3 cloves garlic; 2 tablespoons unsalted butter or olive oil; 2 1/2 teaspoons kosher salt, plus more as needed; 1/2 teaspoon freshly ground black pepper; 2 (32-ounce) cartons low-sodium chicken broth (about 8 cups); 5 sprigs fresh thyme; 2 dried bay leaves; 1 (2 1/2- to 3-pound) rotisserie chicken, or about 1 pound cooked, boneless chicken; 6 ounces dried extra-wide egg noodles (about 3 1/4 cups); 1/2 medium bunch fresh parsley or dill; 1/2 large lemon (optional)