In this recipe, the stuffing is baked outside of the turkey in a baking dish. If you want to stuff your turkey with it, prepare the stuffing through step 2, then follow the directions for microwaving the stuffing as described in the recipe for Roast Stuffed Crisped-Skin Turkey. To make the stuffing a day in advance, increase both the chicken stock and half-and-half by 1/4 cup each and refrigerate the unbaked stuffing 12 to 24 hours; before transferring it to the baking dish, let the stuffing stand at room temperature for about 30 minutes so that it loses its chill.
1. Place cornbread in large bowl. Whisk together stock, half-and-half, and eggs in medium bowl; pour over cornbread and toss very gently to coat so that cornbread does not break into smaller pieces. Set aside.
2. Heat heavy-bottomed, 12-inch skillet over medium-high heat until hot, about 1 1/2 minutes. Add 2 tablespoons butter to pan and swirl to coat pan bottom. When foam subsides, add sausage and cook, stirring occasionally, until sausage loses its raw color, 5 to 7 minutes. With slotted spoon, transfer sausage to medium bowl. Add about half the onions and celery to fat in skillet; sauté, stirring occasionally, over medium-high until softened, about 5 minutes. Transfer onion mixture to bowl with sausage. Return skillet to heat and add remaining 6 tablespoons butter; when foam subsides, add remaining celery and onions and sauté, stirring occasionally, until softened, about 5 minutes. Stir in thyme, sage, and garlic; cook until fragrant, about 30 seconds; add salt and pepper. Add this mixture along with sausage and onion mixture to cornbread and stir gently to combine so that cornbread does not break into smaller pieces. Cover bowl with plastic wrap and refrigerate to blend flavors, at least 1 hour or up to 4 hours.
3. Adjust oven rack to lower-middle position and heat oven to 400 degrees. Butter 10 by 15-inch baking dish (or two 9-inch square or 11 by 7-inch baking dishes). Transfer stuffing to baking dish; pour any liquid accumulated in bottom of bowl over stuffing and, if necessary, gently press stuffing with rubber spatula to fit into baking dish. Bake until golden brown, 35 to 40 minutes.