Preheat the oven to 350 degrees F (175 degrees C). Grease a 7×11-inch baking dish. Place crumbled cornbread in a large bowl.
Melt butter in a large skillet over medium heat. Add onion and celery and sauté until soft, 5 to 7 minutes.
Add sautéed onion and celery to the crumbled cornbread. Stir in chicken stock, eggs, sage, salt, and pepper until well combined. Pour dressing into the prepared baking dish.
Bake in the preheated oven until dressing just starts to turn golden brown around the edges, about 30 minutes.
