I used my 4.5 quart Le Creuset Dutch oven and it worked wonderfully (I love my Le Creuset). For those who don't have experience cooking with cast iron, I let mine heat up on a low heat while I prepared my chicken broth and chopped vegetables. Cast iron is known for retaining the heat, so don't put it on a high heat because your pot will get too hot. I always keep mine in the Lo-2-3 range, never above a 3.
2 tablespoons butter
1 medium onion, chopped
2-3 cloves garlic, minced
2-3 stalks celery, chopped into 1/2 inch pieces
2 medium carrots, chopped into 1/2 inch pieces
8 cups (2 quarts) chicken broth
8 ounces egg noodles
1 ½ cups shredded, cooked chicken
Salt
Pepper
Oregano
A pinch of Crushed red pepper flakes
Heat dutch oven then add butter and saute onion, garlic, celery, and carrots until soft. Pour in chicken broth and bring to a boil. Add the noodles and simmer for 5-7 minutes. Fold in the chicken and seasonings (I'm not the best at measuring seasonings, I just sprinkled in some until it looked good), and continue to simmer until noodles are cooked.
So good! I think the red pepper flakes added a nice touch. I did take it easy on the salt because the chicken broth typically has quite a bit in it already. I did not use a basil leaf, though it is traditional to use in chicken soup. I didn't really feel I needed to use one, though you can throw one in if you like the flavor it adds.
Enjoy!