Spray a 9" by 9" baking dish with cooking spray and set aside.
Preheat an oven to 350F.
In a large skillet brown the Italian sausage meat. Stir from time to time until fully cooked. Place the sausage meat on a paer towel on a plate and allow to drain. Pat it dry and set to one side.
Wipe any excess oil from the skillet. Over medium heaat cook the celery and onions for about 6 minutes until the onions have softened.
Cut the bread into small cubes, about 1/2" in size and place in a large mixing bowl.
Add the cooked onions, celery, cooked sausage meat, beaten egg, chicken stock and Italian seasoning
Using your hands mix all together until well combined and the bread is beginning to soften. Shape the mixture into 8 balls of about 3" diameter and place on prepared dish
Bake at 350F for 30 minutes. The stuffing balls should be beginning to crisp up on top. Serve hot.