Buffalo Chicken and Blue Cheese Cormbread Casserole

1 Tbsp. olive oil
1/2 large onion, chopped
2 carrots, chopped
2 celery stalks, chopped
3 Tbsp. butter
3 Tbsp. flour
2 c. chicken stock + 2/3 c. water
1/2 c. (scant) Frank's RedHot Wing Sauce
1 rotisserie chicken, meat pulled from bones, shredded
1 box Jiffy cornbread mix
1 egg
1/3 c. water
1/2 c. blue cheese crumbles

Preheat oven to 375F. In a large, oven-safe skillet over medium heat, heat olive oil. Add carrots, onion and celery and cook until vegetables are tender. Season with salt and pepper. Push vegetables to the sides of the pan. Melt the butter and add flour. Cook for about 1 minute. Add stock and hot sauce to the pan. Bring to a simmer, and add the chicken to the pan. Simmer until the sauce is thickened, about 2-3 minutes. While the sauce is thickening, prepare the cornbread with egg and water (not milk), and fold in the blue cheese. Drop the cornbread batter on top of the sauce in spoonfuls. Bake until the cornbread is done, about 20 minutes.

(Originally from Rachael Ray, here)