Save space in the oven on the big day with this easy cornbread dressing. I start with a make-ahead buttermilk cornbread that has an extra depth of flavor, thanks to a dash of Dijon. A half hour before everyone sits down to the table, I saute some spicy sausage with Dijon mustard, vegetables, chestnuts and fresh herbs. After folding in the cornbread, the dish goes straight into a serving bowl -- leaving plenty of room for the other sides in the oven.
For the cornbread: Preheat the oven to 400 degrees F. Grease a 9-inch cast-iron skillet with butter.
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.
For the stuffing: Crumble enough of the cornbread into large pieces to make 4 cups. Reserve the remaining cornbread for another use.
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.
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.
Transfer the stuffing to a serving bowl and garnish with the parsley.