Preheat the oven to 350ºF. Butter a large baking dish.
In a large saute pan over medium, heat a bit of olive oil until hot. Add in sausage and cook, breaking up the meat, until browned and cooked through.
Add in celery and garlic and cook until softened about, 6 minutes. Stir in sage and thyme and let cook for about another minute. Transfer to the largest bowl you have and set aside.
To the same pan, add in butter and melt. Toss in shallots and mushrooms and cook over medium heat until mushrooms release all of their liquid. Continue to cook until all the liquid cooks off and the mixture is thick and paste-like. Deglaze with sherry.
Season with salt and pepper. Stir in parsley. Add to the big bowl with the sausage mix.
Whisk eggs and stock together until combined.
Add the dried bread to the big bowl along with the sausage and mushroom mix.
Pour in the stock mixture and stir until everything is combined and the bread has soaked up most of the liquid.
Season with salt and pepper, if needed.
Transfer the stuffing mixture to the prepared pan. Don’t pack the stuffing down in the pan, that will result in a more dense texture! Pour any remaining liquid from the bottom of the bowl over the stuffing.
Cover tightly with foil and bake for 30 minutes.
Increase the oven temperature to 425ºF. Remove the foil, and drizzle the top with olive oil.
Bake again to crisp the top, about another 20-30 minutes. Garnish with more chopped parsley.
Video
Notes
*You can rip the bread up the day before you plan to make the stuffing, lay it out on sheet trays, and leave it out on the counter to dry out. You can also dry the bread by spreading it out on sheet trays and baking them at 350F for 30-40 minutes until the bread is dry and barely golden.**If you want to prep this ahead of time, I suggest drying your bread, and cooking the sausage/duxelle ahead. Then on the day of, all you have to do is mix everything together and bake it!