Preheat the oven to 425 degrees. Butter a 9-inch by 13-inch baking dish. Place the cornbread into a large bowl.
In a large skillet over medium heat, melt the butter and oil. Stir in sausage and cook until lightly browned, about 5 minutes. Add onion and cook until translucent, about 2 to 3 minutes.
To the cornbread, add celery and sausage mixture and toss to combine. Add eggs, dried thyme, 1/2 teaspoon salt, 1/2 teaspoon pepper, and parsley. Stir in turkey stock, a little at a time, until it forms a moist mixture.
Place mixture in prepared baking dish and cover with aluminum foil. Place in the oven and bake, covered, for 45 minutes. Remove foil and bake until crispy, about 20 additional minutes. Serve.
Cornbread: Since we're dressing it up so much with the rest of the ingredients, the semi-homemade route is totally acceptable here. Start with cornbread from a bakery or bake a boxed cornbread mix, like Jiffy, or read on for my tips about how to make cornbread from scratch (see Recipe Tips and Variations). Dry the bread up to 3 days in advance (keep it covered with a dry kitchen towel on counter, or slice and dry in a 300-degree oven for 30 to 40 minutes before proceeding with Step 1).
Chicken broth or turkey broth: Opt for homemade chicken broth or turkey broth if you have it, otherwise boxed or canned stock or broth works, too.
Yield: This recipe makes 10 side dish-sized servings, ideal for enjoying alongside Perfect Roast Turkey for Thanksgiving or any entree the rest of the year. (This is far too delicious to reserve for just one day!)
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Make ahead: After you’ve assembled the stuffing, refrigerate it up to 1 day in advance. When ready to bake, preheat oven to 425 degrees. Keep stuffing tightly covered with foil and bake until mostly heated through, about 45 minutes. Remove foil and bake until crispy edges form, about 10 to 20 minutes longer.