In a large skillet, saute celery and onion in cooking spray over medium heat until soft, about 5 minutes.
While your veggies cook, season your chicken (I use salt-free because the stuffing mix and condensed soup are pretty salty, and they're going on top of the chicken). Arrange chicken in a single layer in a 9x13 pan. It's okay if they overlap slightly.
When veggies are done, turn off heat and add in stuffing mix, condensed soup, water, and cranberries. Stir until evenly mixed and let stand for a couple of minutes so that the bread cubes absorb some of the liquid. If you don't have a large skillet, you might want to do this in a large bowl to hold everything. I always prefer not to dirty up another dish, though.
Distribute stuffing mix evenly over uncooked chicken, about 2/3 a cup per chicken breast.
Bake at 400 for 30 minutes. Broil the top of you like some extra crispy bits. .