In a container or zip-top bag, combine the chicken and marinade ingredients. Marinate for 4-12 hours.
In a large, deep skillet, heat 2 tablespoon oil over medium-high heat. Add the chicken and cook until browned and mostly cooked through, stirring. Remove the chicken form the skillet, leaving any juices in the pan.
Return the skillet to medium heat with another tablespoon of oil. Add the sausage and cook until well browned. Remove the sausage with a slotted spoon and set aside. Leave all fat in the pan.
Add the remaining oil to the pot and turn the heat to medium-high. When hot, add the flour and reduce the heat to medium. Cook, stirring slowly and constantly for 30 to 45 minutes to make a dark brown roux, the color of dark chocolate. Be careful not to let it burn! You can add a little more flour or oil as needed to reach a dough-like consistency.
Add the onions, celery, and bell peppers to the roux and cook, stirring, until softened, 5 to 10 minutes. Add the reserved sausage, salt, cayenne, and bay leaves, stir, and cook for 2 minutes.
Stirring constantly, slowly add the chicken stock to the pot and cook until well combined.
Reduce the heat to medium-low and cook, uncovered and stirring occasionally, for 30 to 45 minutes (skimming off any fat that rises to the surface).
Turn off the heat. Add the reserved chicken, filé powder and remaining dried spices. For deeper flavor, let the gumbo rest for several hours before serving.
Meanwhile, lace the rice, 2 cups of water and a pinch of salt in a saucepan. Bring to a boil, reduce the heat to a simmer, cover and cook for 20-30 minutes, until the grains are tender.
Divide the rice and gumbo between bowls. Top with scallions, parsley and jalapeños to serve.