Make the BBQ sauce and marinade by placing all of the ingredients in a blender and processing until smooth. Divide the mixture in half.
Cover the chicken in half of the BBQ sauce and marinate for 4-12 hours.
Preheat the oven to 375°F.
Place the chicken on a roasting pan, discarding excess marinade. Sprinkle with salt and pepper. Roast for 90 to 75 minutes, or until cooked through and the meat registers 160°F on an instant-read thermometer. Let the chicken rest, covered, for 10-15 minutes before serving.
Meanwhile, bring a large pot of salted water for the pasta. Add the pasta, stirring to prevent clumps. Cook to al dente, according to package instructions, strain and return to the pot, drizzled with oil to prevent sticking.
In a large oven-safe skillet over medium heat, combine the bechamel, milk, stock and pepper. Bring to a boil, stirring constantly. Turn off the heat and fold in the cheeses, stirring until melted and smooth. Stir in the pasta, top with breadcrumbs and bake for 10-15 minutes, until golden on top and melty.
To make the kale, heat the oil in a large skillet. Add the onion and bacon and cook until the onion softens and the bacon is crisp. Add the vinegar and chicken stock and bring to a simmer, scraping up any browned bits on the bottom of the pot. Add the kale, salt and pepper, cover the pot and cook for 10-15 minutes, until the kale is soft and tender.
Carve the chicken and serve with mac and cheese, kale and remaining BBQ sauce.