1Cut the chickens into pieces, reserving the breasts. Place chicken pieces except the breasts in a deep saucepan over medium heat; add the onion, garlic, and chicken broth. Cover the pan and simmer 25 minutes.
2Cut the breasts into halves and add to the saucepan; simmer until the chicken breasts are no longer pink at the bone and the juices run clear, about 20 minutes more. An instant-read thermometer inserted near the bone should read 165 degrees F (74 degrees C). Remove the chicken to a cutting board. Remove the skin and bones from the chicken; cut the meat into bite sized pieces.
3Strain the broth through a fine mesh strainer, reserving the liquid and discarding the onion, garlic, and skimmed fat. If you have less than 3 cups of reserved liquid, add water to make 3 cups. If you have more than 3 cups, return to the pan and bring to a boil; cook until volume of liquid reduces to 3 cups.
4Combine the chili powder, almonds, banana, cinnamon, salt, tortilla pieces, sesame seeds, and pine nuts in a blender. Blend on low, slowly adding the reserved liquid in a stream until the mixture is smooth. Pour the mixture and remaining liquid into a large saucepan over medium heat. Add the butter and chocolate; cook and stir until the butter and chocolate have melted. Stir the chicken pieces into the sauce; continue cooking until the chicken is heated completely through, 5 to 10 minutes.