Preheat oven to 350F.
Cook sausage in a medium sized pan on stove top until there isn't any pink left. If you’re using sausage without casing, break it up while it cooks. If using whole sausage, either remove from casing prior to cooking OR cut into pieces of desired size after it is cooked.
In a medium or large pan, sauté onions and celery (and mushrooms, if using) in the butter or fat of your choice. Then add cooked, drained, crumbled sausage, Croutonz, nuts, poultry seasoning or fresh herbs, 1 cup of stock, salt and pepper. Toss well and let rest for 10 minutes, tossing occasionally.
Mix the remaining 3/4 cup stock with egg. Add stock/egg mixture and any other desired add-ins. Add more stock if a moister stuffing is preferred.
Bake in a well-buttered casserole or skillet. For more crusty surface bits, use a larger one. Bake 20 to 30 minutes or until thoroughly heated and crusty, as desired.
Enjoy!