Crumble the cornbread using your fingers until it breaks apart. Transfer to a cookie sheet tray lined with parchment paper along with the cubed rolls and spread out. Bake for 30 minutes.
In the meantime, add the butter to a large frying pan over low to medium heat and sweat the onions and celery for about 10 to 12 minutes while occasionally stirring. Set aside once done.
When the bread is done drying out a bit, add it to a large bowl along with the cooked vegetables, poultry seasoning, velouté, chicken stock, salt, and pepper, and gently mix until combined.
Pour in the whisked eggs and again gently mix them together until it is combined. Transfer the mixture to a 13x9 casserole dish, cover it, and bake at 350° for 25 minutes.