Preheat the oven to 350ºF and grease a baking dish with cooking spray (or with melted butter).
In a large skillet over medium-high heat, cook the sausage, breaking it up with a wooden spoon until cooked through. Transfer it to a large bowl, leaving some of the drippings in the skillet.
Place the bread cubes in the same large bowl (on top of the browned sausage).
In the same skillet, melt the butter over medium heat. Add the onions, celery and apples and cook, stirring occasionally until soften, about 6-7 minutes.
Add the garlic and poultry seasoning and cook until aromatic, about 1 minute.
Add the sautéed vegetables to the bowl with the sausage and the bread cubes. Toss gently. Pour the chicken broth, egg, rosemary, sage and parsley, salt and pepper. Mix until the bread is moistened and soft.
Transfer the stuffing to the prepared baking dish and bake for 55 to 65 minutes, uncovered or until golden brown. If it starts browning too much on top, cover it with a piece of foil.