Heat the oil, or melt the butter, in a large skillet set over medium heat. Add the onion, celery and apples and cook until tender, about 5 minutes. Place the mixture in a large bowl. Add the bread, sage, apple juice, stock and cranberries. Season with salt and pepper and toss to combine.
Preheat the oven to 350 degrees F. Spoon the dressing mixture into a lightly oiled or buttered 9" x 13" baking dish. Cover the dressing with foil and bake for 30 minutes. Uncover and bake 15 minutes more, or nice and hot and nicely coloured on top.
Note: Udi’s brand gluten-free bread was used when testing this recipe. If you choose to use dried sage leaves, they are available in the bottled herb and spice aisle. It's made from crumbled sage leaves; don't mistake it for finely ground sage.