1- In a large, heavy-bottom pot, combine 1 cup flour and 2/3 cup oil to make the roux. Cook over medium-low heat, stirring constantly for 30 to 45 minutes until it reaches a dark chocolate color with a soft, dough-like texture, taking care not to burn.

2- Brown the sausage slices in a separate skillet over medium-high heat until well browned on both sides; remove and set aside.

3- Deglaze the sausage pan with ½ cup chicken broth, scraping up drippings, and add this liquid to the pot with the roux.

4- Add the remaining 5½ to 9½ cups chicken broth along with diced celery, bell pepper, onion, green onions, parsley, garlic, and mix well with the roux.

5- Bring to a boil over medium heat, cook for 5 to 7 minutes until vegetables soften, and skim off foam.

6- Stir in 1-2 tablespoons Cajun seasoning to taste. Add uncooked shrimp now if using and cook for 2 minutes.

7- Add chicken, browned sausage, and pre-cooked shrimp if applicable. Adjust seasoning with salt, pepper, chicken bouillon paste, or additional broth as needed.

8- Serve warm over cooked rice. The flavor improves after resting overnight, making it even better the next day.