Preheat oven to 350 degrees
Heat a large saute pan over medium heat, add in sausage and cook, breaking up the meat up as you go, until the sausage has cooked through.
Remove sausage and drain grease, set aside.
In same pan add add 1/2 cup butter, onions and celery and cook until tender.
Add chicken broth and season with salt and pepper.
In a large bowl place bread cubes, sausage, onion/celery/broth mixture & apple.
Stir until combined.
Re-taste and re-season, if necessary.
Transfer mixture into 9x13 pan and cook in preheated oven until warmed through, about 40 minutes uncovered