Preheat the oven to 350F.

Heat the oil in a large skillet and add the sausage meat. Cook for about 5 minutes or until almost browned all over, then add chopped celery, onion powder, and garlic. Cook for another 5 minutes.

Transfer the bread and cooked sausage to a large bowl. Add the chicken broth, beaten egg, and the sage. Season with salt and pepper.

Stir well, then spoon the mixture into a baking dish. Cover with foil, then roast in a preheated oven for 20 minutes. Remove the foil, then cook for another 8-10 minutes or until the top is crispy.