Grease a 10-inch cast iron skillet and place on center rack in the oven. Preheat oven to 425°F.

In a large mixing bowl, combine 1 cup yellow cornmeal, 1 cup all-purpose flour, 3 tablespoons granulated sugar, 1 tablespoon baking powder, and 1 ½ teaspoons kosher salt. In a separate bowl, whisk 2 large eggs, ½ cup melted butter, and 1 cup whole buttermilk. Add the wet ingredients to the dry ingredients and stir until just incorporated.

Pour the batter into the preheated skillet and smooth the top. Bake until cornbread is golden yellow, 16 to 19 minutes. Immediately remove the cornbread from the skillet and allow to cool.

For the cornbread dressing, preheat oven to 350°F.

Crumble the cornbread into small pieces (makes about 5 cups). Combine the crumbled cornbread and 1 (14 ounce) bag stuffing mix in an extra large mixing bowl (or stock pot) and toss to combine.

Melt 1 stick butter in a large skillet over medium heat. Add 2 cups finely chopped sweet onion and 1 ½ cups finely chopped celery and sauté, stirring frequently, until soft and translucent, 10 to12 minutes. Add the onion and celery to the cornbread mixture.

Melt the remaining stick of butter. In a large mixing bowl, combine the butter, 5 cups chicken or turkey stock, 5 large eggs, and 2 teaspoons dried sage, and whisk to combine. Add to the cornbread mixture and mix until thoroughly incorporated. Season generously with kosher salt and black pepper.

Pour into a greased 9x13-inch casserole dish. Bake, uncovered, until the dressing is set and golden brown, about 45 minutes to 50 minutes.