Chicken and Sausage Gumbo

Melt 4 tablespoons butter in a large stockpot over medium-high heat. Working in batches, brown the sausage, 2 minutes per side; transfer to a large bowl. Season the chicken with 1/4 teaspoon each salt and pepper and cook until golden brown, 2 minutes per side; transfer to the bowl. When cool, cut the sausage and chicken into 1-inch pieces (they will only be partially cooked). Reduce heat to medium, add the flour and oil to the pot and cook, stirring frequently, until the mixture is a deep golden brown, 12 to 15 minutes. Add the onions, celery, peppers, and garlic and cook, stirring occasionally, until the vegetables are tender, 10 to 12 minutes. Meanwhile, melt the remaining tablespoon butter in a large skillet over medium heat. Working in batches, cook the okra, turning once or twice until golden brown, about 6 to 7 minutes, adding more butter as necessary. Add the broth to the pot along with the sausage, chicken, and okra (and any juices that have accumulated in the bowl). Stir in the tomatoes, collards, thyme, bay leaves, and 3 teaspoons salt. Bring to a boil, then reduce heat and simmer until slightly thickened, 25 to 30 minutes (be careful not to overcook, or the okra will become slimy). Discard the bay leaves and stir in the filé powder (if using). Serve with cooked rice, parsley, and scallions, if desired.