Cook noodles in heavily salted water according to package directions for al dente.
Dice up cooked chicken. I used breast tenders that I poached in salted water.
In a large pot, melt butter over medium heat. Whisk in flour and cook for one minute to make a roux. Slowly add milk, whisking constantly until the roux is well incorporated. Bring to a simmer then reduce heat to low. Simmer three to four minutes until sauce thickens a bit. Add sour cream and heat through.
Add cheese to milk mixture, whisking constantly. Add black pepper and nutmeg. Salt as needed.
Add diced chiles, cooked chicken, and thawed (or fresh, cooked) cut green beans. Combine well and heat through. Serve warm Chicken Chile Mac and Cheese immediately. Garnish with chives if desired. Sink your teeth into this one!