Preheat your oven to 350 degrees F. Grease a 9×13 inch baking dish.
Crumble the prepared cornbread into a large bowl. You need about 8 cups of crumbs.
In a skillet over medium heat, sauté the celery and onion in 2 tablespoons of the melted butter until soft, about 5 to 7 minutes.
Add the sautéed vegetables to the bowl with the cornbread crumbs.
In a separate bowl, whisk together the remaining melted butter, eggs, chicken broth, sage, thyme, salt, and pepper.
Pour the liquid mixture over the cornbread and vegetable mixture. Gently toss everything together until the cornbread is evenly moistened. Do not overmix.
Transfer the dressing mixture to the prepared baking dish.
Bake for 40 to 45 minutes, or until the top is golden brown and the center is set.
Let the dressing rest for 10 minutes before serving.
Notes
For a richer flavor, use homemade cornbread baked without sugar.
You can prepare the cornbread and chop the vegetables a day ahead of time.