Make the Creole spices first by mixing spices together in bowl.

Transfer spices to clean container with tight-fitting lid. Cover and store until needed. Begin the gumbo by heating rendered chicken fat or bacon fat in large cast-iron or heavy-bottomed pot over high heat. Whisk flour into hot fat to make a roux. It will immediately begin to sizzle. Reduce heat to moderate and continue whisking until roux takes on a deep brown color, about 15 minutes. Add diced onions, stirring them into roux with wooden spoon. Reduce heat to medium-low and continue stirring until roux is a glossy dark brown, about 10 minutes. Add celery, bell peppers, and garlic; cook, stirring, for about 3 minutes. Add chicken pieces, andouille sausage, thyme, stock, and bay leaves. Sprinkle in Creole spices and bring gumbo to a boil, stirring occasionally.

Reduce heat to medium-low and simmer for 45 minutes. Stir occasionally and skim off fat from surface of gumbo every so often. Add okra and season with salt and pepper if needed; add several dashes of fil. powder. Simmer for another 45 minutes, continuing to skim fat off surface of gumbo. Remove the bay leaves. Keep warm until serving. Serve with rice.