Preheat your oven to 350°F (175°C) and lightly grease a 9x13 inch baking dish.

In a skillet over medium heat, sauté the diced onion and celery in a small amount of butter until softened, about 5 minutes.

In a large mixing bowl, combine the crumbled cornbread, shredded chicken, chopped hard-boiled eggs, and the sautéed vegetables.

In a separate bowl, whisk together the 2 cups of chicken broth, cream of chicken soup, melted butter (1/2 cup), poultry seasoning, and black pepper until smooth.

Pour the liquid mixture over the dry ingredients and stir gently until well combined. The mixture should be moist but not soupy.

Transfer the mixture to the prepared baking dish and spread it out evenly.

Bake for 40-50 minutes, or until the top is golden brown and the center is set.

While the casserole bakes, prepare the gravy. Melt 4 tablespoons of butter in a saucepan over medium heat. Whisk in the flour and cook for 1-2 minutes until bubbling.

Gradually whisk in the chicken stock, stirring constantly to prevent lumps. Simmer until thickened, then stir in the heavy cream if using. Season with salt and pepper to taste.

Remove the casserole from the oven, let it rest for 5 minutes, and serve warm topped with the homemade gravy.