Spread the bread cubes evenly on baking sheet(s) - Place in lower third of the oven and allow to bake until bread is completely dried (apx 45 minutes); NOTE: Give the bread cubes a stir and rotate baking sheets every 15 minutes - Remove from heat and set aside until needed
Increase oven temperature to 350ºF
Melt butter in a large skillet over medium heat - Add sausage meat and cook (making sure to break it up as you go) until browned and cooked through (apx 8 minutes) - Add the celery, carrot, onion, mushrooms, garlic, and sage - Sauté until vegetables are softened (apx 10 minutes) - Remove from heat and add half of the chicken broth - Thoroughly combine
In a large mixing bowl, whisk together the remaining chicken broth, parsley, eggs, salt, and pepper until well combined - Transfer the sausage mixture to the mixing bowl and thoroughly combine - Gently fold the bread cubes into the sausage/egg mixture until evenly mixed
Butter a 9"X13" baking dish or 3 quart casserole - Transfer the mixture to the buttered dish and gently 'spread' until level - Cover tightly with aluminum foil
Place in the center of the oven and allow to bake for 45 minutes - Remove foil and continue to bake until the top is browned and 'crispy' (apx 15 minutes more)
Remove from oven and allow to sit for 10 minutes - Serve hot