Meanwhile, melt 1½ tbsp butter in a large pan over medium heat. Add chopped chestnuts. Season with salt and pepper. Stir often, until chestnuts are golden and fragrant, about 5 min. Use a slotted spoon to transfer chestnuts to a large bowl. Wipe out the pan with paper towels.

Melt 2 tbsp butter in the same pan over medium heat. Add the onions and celery. Season generously to taste with salt and pepper. Sweat the vegetables until softened, about 4-5 min.

Add in the sausage and season again with salt and pepper. Cook, using the back of a wooden to break up the sausage into bite-sized pieces. Cook until the sausage begins to brown, about 4-5 min. Add in garlic and sauté until fragrant, about ½ min. Add in the thyme, parsley, and rosemary. Cook until fragrant, about 1 min. Remove pan from heat and stir in ½ cup of stock. Transfer to large bowl with chestnuts.

In a large measuring cup, add 1 cup of chicken stock and eggs. Whisk until well combined.

Slowly pour the egg mixture over the sausage mixture. Add the toasted cornbread. Gently fold everything until evenly combined, taking care not to mash the cornbread. (The mixture should look wet. If you like your stuffing really wet, add another tbsp or two of stock, but not too much, lest it remain soggy).

Transfer the mixture to the prepared baking dish. Cover with aluminum foil. Bake covered for 30 min. Melt remaining 2 tbsp of butter. Remove stuffing from oven, uncover and brush with melted butter. Continue to bake, uncovered now, for 20-30 min or until the stuffing is hot and the top is golden and crisped.

Remove from oven and let cool for a few min. Sprinkle with fresh herbs and enjoy.