Begin by cutting the whole-wheat bread into small cubes, roughly 1 inch in size. Spread the cubes out on a baking sheet and allow them to dry overnight at room temperature.

While the bread dries, finely dice the apples, onion, and celery. Set the apples aside to keep them fresh.

In a large skillet, heat olive oil or butter over medium heat. Once hot, add the diced onion and celery, sauté for 5-7 minutes until soft and translucent.

In a mixing bowl, combine dried bread cubes, sautéed onion and celery, and the diced apples. Add sage, salt, and pepper. Gradually pour in broth to moisten the mixture.

Transfer the mixture into a greased baking dish, cover with foil, and bake in a preheated oven at 350°F (175°C) for 25-30 minutes.