Preheat your oven to 300°F (150°C). Cut the sourdough bread into uniform cubes, approximately one inch each. Spread the cubes on a large baking sheet in a single layer and bake for 25 minutes, stirring halfway through for even browning.

Raise the oven temperature to 325°F (160°C). In a large skillet, melt 4 tablespoons of unsalted butter over medium-high heat. Add diced yellow onion and celery along with a pinch of salt and pepper. Sauté for 7-8 minutes until soft and fragrant.

Incorporate diced Honeycrisp apples and dried cranberries into the skillet. Continue to cook for an additional 3-4 minutes, allowing the apples to soften slightly.

In a large mixing bowl, combine your toasted sourdough bread cubes with the sautéed mixture. In a separate bowl, whisk together one beaten egg and 2 cups of chicken broth. Pour this mixture over the bread and vegetables, folding gently until evenly coated.

Transfer the stuffing to a greased 9x13-inch baking dish. Cover with aluminum foil and bake in the preheated oven for 15 minutes. Remove the foil and bake for an additional 20 minutes until the top is golden brown and crispy.