Preheat oven to 350 degrees F.
Cook bacon in a heavy skillet until crisp. Turn heat down and add onions and celery; saute until tender, about 6 minutes. Add the thyme and sage and saute until fragrant. Stir in pecans.
In a large bowl, add the cornbread mix, bacon and vegetables, and stir in the chicken broth. Add to a 13 by 9 by 2-inch casserole dish. Add butter slices to the top of the casserole and cover with foil. Bake for 30 minutes then remove foil and cook until top is crisp, about 15 more minutes.