For the cornbread:

Unsalted butter, for the pan

1 cup cornmeal

1 cup all-purpose flour

2/3 cup granulated sugar

3 1/2 teaspoons baking powder

2 teaspoons kosher salt

1/2 cup buttermilk

1/2 cup whole milk

1/3 cup canola oil

2 tablespoons Dijon mustard

1 large egg, beaten

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For the stuffing:

1 pound spicy pork sausage

2 tablespoons onion powder

1 tablespoon garlic powder

2 teaspoons ground fennel seed

1 teaspoon celery salt

Kosher salt and freshly ground black pepper

1 cup chopped carrot

1 cup chopped celery

1 cup peeled, roasted chestnuts, chopped

1 cup chopped fennel

1 cup chopped Spanish onion

2 tablespoons minced garlic

1 tablespoon minced fresh sage leaves

1/2 cup white wine

2 cups chicken stock or low-sodium chicken broth

1/4 cup Dijon mustard

2 teaspoons chopped fresh parsley

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1. For the cornbread: Preheat the oven to 400 degrees F. Grease a 9-inch cast-iron skillet with butter.
2. Combine the cornmeal, flour, sugar, baking powder and salt in a large bowl. Stir in the buttermilk, whole milk, oil, Dijon mustard and egg until smooth. Pour the batter into the prepared skillet and bake until a toothpick inserted into the center comes out clean, about 25 minutes. The cornbread can be made up to 1 day in advance. Wrap tightly in several layers of plastic wrap and store at room temperature.
3. For the stuffing: Crumble enough of the cornbread into large pieces to make 4 cups. Reserve the remaining cornbread for another use.  
4. Add the sausage to a large skillet over medium heat and cook, breaking up with a wooden spoon, until the fat starts to render, about 8 minutes. Add the onion powder, garlic powder, fennel seed and celery salt and season with salt and pepper. Once the meat starts to brown and crisp, add the onion, carrot, celery, chestnuts, fennel, garlic and sage. Cook, stirring occasionally, until the meat is browned, the carrots become soft and tender and the onions are translucent, about 10 minutes. 
5. Add the white wine and scrape up any browned bits from the bottom of the pan with a wooden spoon. Bring the wine to a boil and cook until mostly evaporated, about 3 minutes. Stir in the chicken stock and Dijon mustard and bring to a simmer. Fold in the cornbread until completely incorporated and the bread is moist and heated through, about 3 minutes. Season to taste with salt and pepper.  
6. Transfer the stuffing to a serving bowl and garnish with the parsley. 

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