Pennsylvania Dutch Chicken Noodle Soup

In a large heavy pot, heat the butter over medium heat until hot, stir the onions, carrots, celery, 3/4 teaspoon salt, and 1/2 teaspoon pepper and cook, stirring occasionally, until golden, 8 to 10 minutes. Stir in the flour and cook until fragrant and nutty, about 4 minutes. Whisk in the stock and chicken and bring to a boil. Stir in the egg noodles and cook until the chicken is cooked through and the noodles are very tender, 20 to 25 minutes. Season the soup with salt and pepper to taste, then serve sprinkled with the dill.