In a large skillet over medium heat, add butter, onions, celery, bell pepper, and apple. Saute for about 15 minutes until very soft.
Season the vegetable mixture with salt and sage. Add the sausage, and continue to cook until sausage is cooked through.
Add the apple cider and chicken broth, and simmer until the liquid is reduced to half.
Add the cornbread, and stir well to combine, then remove from heat.
Once the mixture has had 5 minutes to cool down, add a beaten egg, and then stir to coat.
Perheat oven to 400 degrees. Bake stuffing balls for 20 minutes, or until lightly browned on top and heated through.
Serve as a side at a holiday meal, or as a main course for a festive winter dinner.