Prepare Bread Cubes
If the bread is fresh, cut it into cubes and toast in a 350°F (175°C) oven for 10–15 minutes until slightly crisp. Let cool.
Cook Aromatics
In a large skillet, melt the butter over medium heat.
Add onion and celery, and sauté until softened, about 5 minutes.
Stir in diced apple, cranberries, thyme, sage, salt, and pepper. Cook for 2–3 more minutes.
Combine Ingredients
In a large mixing bowl, combine the toasted bread cubes with the sautéed mixture. Toss to combine.
Add Liquid
Whisk together the chicken or vegetable broth and the beaten egg. Pour over the bread mixture, stirring gently to moisten evenly.
Bake the Stuffing
Preheat oven to 375°F (190°C).
Transfer the stuffing mixture to a greased 9x13-inch baking dish.
Cover with foil and bake for 25 minutes.
Remove the foil and bake for an additional 15–20 minutes, or until the top is golden and crisp.