Slow roast chicken until it removes easily from the bone. Separate chicken from bone and chop into small pieces. Season chicken with rotisserie chicken seasoning, poultry seasoning, black pepper, and salt.
In a large skillet, heat chicken fat. Stir in flour and salt. Heat milk and gradually add to flour mixture, whisking out any lumps as you go. Stir constantly until thickened; then add chicken.
Serve chicken gravy over and between layers of buttered green chili corn bread.