Spread out the cubed bread on a cookie sheet tray lined with parchment paper and bake in the oven for 25 to 30 minutes or until crisp and firm. Set aside.
While the bread is baking add a ½ stick of butter to a large frying pan or rondeau over medium-high heat and cook the sausage until broken up, lightly browned, and cooked throughout.
Remove the sausage from the pan or pot and add the remaining ½ stick of butter.
Add in the onions and cook for 4 to 5 minutes or until lightly browned and then add in the mushrooms and cook for a further 8-10 minutes while occasionally stirring until lightly browned.
Place in the celery and garlic and cook for 4 to 5 minutes or just until the celery is tender.
Transfer the cooked vegetables, sausage, and baked cubed bread to a very large bowl.
Next, add in the herbs, salt, pepper, and chicken stock and mix gently until combined. See note about chicken stock.
Pour in the whisked eggs and then again gently mix until combined.
Transfer the mixture to a 13x9 casserole dish and cover with foil.
Bake at 350° for 25 minutes, then remove the foil and bake for a further 20 minutes or until the top is lightly browned.
Serve garnished with fresh chopped parsley.
Notes
Make-Ahead: You can make this recipe up to 1 hour ahead, keep it covered and warm at low temperatures in the oven until ready to serve.How to Reheat: Add the desired amount of dressing to a casserole dish or pan, drizzle on ¼ to 1/3 cup of chicken stock, and cover with foil. Bake in the oven at 350° for 15 to 20 minutes or until warmed.How to Store: Cover and keep in the refrigerator for up to 4 days. You can cover and freeze it for up to 3 months. Thaw it in the refrigerator for 1 day before reheating.Use a little bit of stock at a time, and you may find that you need less or more when mixing it in.When mixing the stuffing together, do so gently so that the bread or other ingredients do not break apart.