Preheat oven to 450ºF. Adjust oven rack to second highest position.

Carefully butterfly pork loin without cutting all the way through; open like a book. Cover with plastic wrap; pound meat to a half-inch thickness, using a meat mallet or small heavy skillet. Sprinkle evenly with Creole seasoning. Spoon two to three cups cooled jambalaya over pork and spread evenly, leaving a half-inch border all around. Evenly roll pork to form a uniform log, jelly roll style. With fat-side up, evenly tie roast at two-inch intervals with butcher twine. Season with Creole seasoning. Place in hot oven; close oven door and immediately reduce heat to 375ºF. Roast 40 minutes or until a thermometer placed in direct middle registers 145ºF. 

Increase heat to broil. Carefully broil about five minutes or until outside is golden and a thermometer placed in direct middle registers at least 160ºF. Remove from oven. Immediately cover with foil; let rest 15 minutes. Remove twine; cut into one and a quarter-inch slices and arrange on a warm serving plate. 

For the Jambalaya

Sauté sausage in a small Dutch oven over medium-high heat until lightly browned. Add onion, celery, bell pepper, and garlic; sauté five minutes. Add rice and creole seasoning; sauté two minutes. Add broth; stir well. Bring to a boil; cover with lid, reduce heat to low, and simmer 30 minutes. Remove from heat. Add green onions; stir well. Allow jambalaya to cool completely before stuffing pork loin.