Preheat your oven to 425°F (220°C).

Place ½ cup of butter in a 13×9-inch baking pan and heat it in the preheated oven for about 4 minutes or until melted.

In a large mixing bowl, combine the white cornmeal, all-purpose flour, sugar, baking powder, salt, and baking soda.

Whisk in 3 of the large eggs and the buttermilk until the mixture is well combined.

Carefully pour the hot melted butter into the cornbread batter, stirring until fully incorporated.

Then, pour this cornbread batter into the preheated baking pan.

Bake the cornbread at 425°F for approximately 30 minutes, or until it turns golden brown.

Allow it to cool.

Crumble the cooled cornbread into a large bowl, and then stir in the soft breadcrumbs.

Set this mixture aside.

In a large skillet, melt the remaining ½ cup of butter over medium heat.

Add the finely diced onions and celery, and sauté them until they become tender.

Stir in the chopped sage and sauté for an additional minute.

Combine the sautéed vegetables, the remaining 4 large eggs, condensed chicken broth, and black pepper with the cornbread mixture.

Mix everything together until it’s well combined.

Lightly grease a 13×9-inch baking dish and an 8-inch square baking dish.

Evenly distribute the cornbread mixture between these two dishes.

Cover the dishes and refrigerate for at least 8 hours, allowing the flavors to meld.

Preheat your oven to 375°F (190°C).

Bake the cornbread dressing, uncovered, for 35 to 40 minutes or until it turns golden brown.